Mr Rebelo said the pace of construction must be accelerated if the venues are to be ready by this December.

Brazil has seen two months of protests against corruption and overspending in the preparation for the World Cup and the 2016 Olympics in Rio.

Only one of the six stadiums under construction is on schedule.

The opening match venue in Sao Paulo is 84% built and is expected to be ready by the end of the year, as demanded by the World Cup organisers, Fifa.

There are bigger concerns over the pace of work at the arenas being built in Manaus, Curitiba, Cuiaba, Porto Alegre and Natal, which are from 71% to 79% ready.

"This must be seen as a warning. We cannot keep on the same rhythm, or we will not deliver them on time," said Mr Rebelo.

"It is possible to intensify. We are able to meet the deadlines, but it should be noted that it will require us to speed up the construction."

He warned that no extra government funds would be given to construction companies to have the work finished on time.

"There will be no budget increase, because, for example, instead of paying 10 workers during two months, you can pay 20 to work for 30 days," Mr Rebelo explained.

The World Cup will be played in 12 stadiums across the country.

The opening match is due to take place at a brand-new venue being built in the outskirts of Sao Paulo on 12 June.

The final is scheduled for the 13 July in country's most famous football stadium, the Maracana in Rio de Janeiro.

Six of the World Cup venues were put to test in June during the Confederations Cup, won by Brazil with a 3-0 victory over world champions Spain in the final.

Fifa has previously said that the World Cup will go ahead in Brazil as planned.

"The first game will happen in Sao Paulo, the final will be in Rio. There is no plan B," said Fifa general-secretary Jeremy Valcke during the Confederations Cup.

The incident happened on 23 April in a town in Kashgar prefecture. Fifteen officials or security personnel were among those killed.

China said it was a planned attack by a "violent terrorist group".

But other accounts dispute this, attributing the confrontation to ethnic tensions in the restive region.

Xinjiang is home to the Muslim Uighur minority, who make up about 45% of the region's population but say an influx of Han Chinese residents has marginalised their traditional culture.

The authorities often blame violent incidents in Xinjiang on Uighur extremists seeking autonomy for the region.

Uighur activists, meanwhile, accuse Beijing of over-exaggerating the threat to justify heavy-handed rule.

Verifying reports from Xinjiang is difficult.

While foreign journalists are allowed to travel to the region, they frequently face intimidation and harassment when attempting to verify news of ethnic rioting or organised violence against government authorities.

The BBC team that visited the site of the incident to try to clarify details were taken by police to a government compound and subsequently ordered to leave.

'Religious extremism'

The two men sentenced to death by Kashgar's Intermediate People's Court on murder and terrorism charges were named in state media as Musa Hesen, the co-founder of the "terrorist group", and Rehman Hupur.

Three other men were jailed for terms ranging from nine years to life.

The group had been "carrying out illegal religious activities (and) promoting religious extremism", Xinhua news agency reported, citing a court statement. They had also "made 10 explosive devices and carried out explosive tests", it said.

The violence was sparked when three officials saw suspicious behaviour at a house, Chinese reports say.

Residents seized the officials and several more police who came to the scene, many of whom burned to death when the house was set on fire. Security personnel shot six suspects, Chinese reports say.

But a group of local people in Selibuya town, where the clashes happened, told the BBC that the violence involved a local family who had a long-standing dispute with officials who wanted the men to shave their beards and the women to stop wearing full veils.

A spokesperson for the World Uighur Congress, an umbrella organisation of Uighur groups, also disputed the government's version, saying the clashes were a result of a government clean-up campaign.

The incident comes amid rumbling ethnic tensions between the Muslim Uighur and Han Chinese communities.

In 2009 almost 200 people - mostly Han Chinese - were killed in deadly rioting in Xinjiang's capital, Urumqi.

There have been sporadic eruptions of violence since then - in June 2013, 35 people were killed in rioting in the township of Lukqun, about 200km (120 miles) south-east of Urumqi.

Residents of Kesennuma in Miyagi prefecture voted to scrap the Kyotoku Maru No 18 - swept inland by a giant wave triggered by a strong earthquake.

There had been plans to preserve the boat as a monument.

The tsunami and earthquake on 11 March 2011 left more than 18,000 people dead or missing in Japan.

The magnitude 9.0 quake, Japan's most powerful since records began, also triggered a nuclear accident at the Fukushima Daiichi nuclear plant.

The earthquake struck about 400km (250 miles) north-east of Tokyo. The tsunami it triggered hit the north-eastern coast of the main island of Honshu, sweeping away cars, ships and buildings, and crushing coastal communities.

Kesennuma, with an estimated population of 70,000, was one of the hardest hit by the tsunami.

After the disaster, people started visiting the marooned 60-metre (200-foot) boat to pray, take photographs and leave flowers.

But last week, it was announced that the majority of the city residents had voted to have the ship broken up for scrap.

"Our city has decided to demolish the vessel since nearly 70% of residents did not want to preserve it," a local official was quoted by Agence-France Presse news agency as saying.

"It's just a constant reminder of the terrible disaster," resident Yoshimi Abe told the Associated Press news agency. "When I walk by it every morning, my heart aches."

City Mayor Shigeru Sugawara expressed disappointment that the boat, which he said was a "visible symbol of what happened here", would be destroyed, but he said the decision had been made.

The vessel may be taken apart in a few weeks, reports say.

Kyodo news agency reports that a non-profit ship recycler has been contacted to dismantle the vessel, which is owned by fishing company Gisuke Gyogo in Fukushima prefecture.

A plane from London was the first to land at Jomo Kenyatta International Airport at 06:30 local time (03:30 GMT), Kenyan airport authorities said.

Other planes from Bangkok and Kilimanjaro also landed on Thursday.

The cause of the fire is not yet known. Kenyan authorities say no serious injuries were reported.

The Nairobi airport is a regional hub serving more than 16,000 passengers daily and its closure caused widespread disruption.

International flights into the city had been diverted to other airports in Eldoret and the coastal city of Mombasa.

On Wednesday the interior ministry announced the resumption of domestic and cargo services.

The fire took about four hours to bring under control, by which time the arrivals hall had been gutted.

On Wednesday, a government official said up to 300 tonnes of highly radioactive water may be flowing into the sea every day.

Prime Minister Shinzo Abe said the government would take "firm measures" to contain the leak.

One proposal being considered is to freeze the ground around the plant.

The plant was badly damaged by an earthquake and tsunami in 2011. It has been hit by a spate of water leaks and power failures in recent months.

"Rather than relying on [plant operator] Tokyo Electric, the government will take measures," Mr Abe told reporters on Wednesday.

"This is an urgent matter that needs to be addressed."

Penn Bowers, a research analyst at CLSA Asia Pacific in Tokyo, told the BBC that the government appeared to be set to take a bigger role in the Tepco clean-up.

"[The government has] invested capital in the company to date but not taken any direct operational steps at the facility until now," he said.

Contaminated water may have been leaking from the plant into the sea ever since the 2011 nuclear disaster, an official at Japan's energy ministry said.

The government believed that up to 300 tonnes of radioactive water could be leaking into the sea on a daily basis, the official added.

However, plant operator Tokyo Electric Power Company (Tepco) told the BBC that the figure was only a guess, and that it was not clear how much water flowing into the sea was contaminated with radiation.

The contaminated water is thought to have come from the 400 tonnes of groundwater pumped into the plant every day to cool the reactors, after cooling systems were knocked out by the tsunami.

The government is discussing proposals to build a wall of frozen ground around the reactor buildings to prevent further leaks. Reports suggest this could cost up to 40bn yen ($400m; £260m).

Chinese exports rose 5.1% compared with a year earlier while imports gained 10.9%.

The rises were wild swings from June's data, which showed exports had fallen 3.1% and imports had dropped 0.7%.

Last month, the government reiterated its 7.5% economic growth target for this year, after expansion slowed in the second quarter.

The July data meant the trade surplus narrowed to $17.8bn (£11.5bn), down from June's $27.1bn.

Analysts said the results were surprisingly good, but warned against being too optimistic.

"July seems to reflect a return to a 'normal', relatively uninspiring trend after a weak June, rather than the beginning of an acceleration in growth," said Alaistair Chan from Moody's Analytics in a report. "While the worst seems to be over, the upturn will be relatively flat."

China has seen its manufacturing and exports sector slow in the wake of the global financial crisis that has sapped demand for its products. These sectors were the main drivers of the economy for China through its years of blistering growth.

In June, China saw export growth decline for the first time in 17 months.

Analysts said the rise in exports was a stabilisation.

"The higher-than-expected export growth is easier to understand and this kind of growth rate still reflects that external demand just picked up very slowly," said Wei Yao from Societe Generale in Hong Kong. "It is more of a stabilisation rather than a sharp rebound."

However, she said the sharp rebound in imports was harder to explain.

"Even though the government had announced some supportive measures, they should not show effects so soon. The fundamentals in the economy did not support such a strong rebound," she said.

Chinese data in general, and especially trade data, is often seen as being unreliable, with some suggesting that false invoicing and other factors could skew the numbers.

The data comes after mixed data from the Chinese economy last week, with official and private surveys of the country's manufacturing sector showing differing results.

The Chinese economy posted growth of 7.8% in 2012, its slowest pace since 1999.

Data showed it had since slowed further, with growth in the April-June period faltering to 7.5% compared to the previous year, from 7.7% in the first quarter.

At about 07:30 local time (11:30 GMT), a wrecking machine smashed through the house to begin the demolition.

Castro, 53, a former school bus driver, was sentenced to life in prison last week after pleading guilty to dozens of rape, kidnapping and other charges.

He abducted Michelle Knight, 32, Amanda Berry, 27, and Gina DeJesus, 23, from Cleveland streets between 2002-04.

Authorities say he kept the women chained for long periods in the house, beating and starving them and forcing one of them to miscarry several pregnancies.

The women were freed in May after one of them escaped while Castro was out of the house and summoned help.

He was sentenced to life in prison plus 1,000 years on 1 August.

On Wednesday morning, Ms Knight spent several minutes in front of the house where she was held for 11 years as Castro's captive, a period she had described at his sentencing as "hell".

Then a crew of workers wearing high-visibility jackets tore the house down using heavy demolition kit, as neighbours and television crews looked on. Onlookers cheered.

Within minutes, the house was reduced to a pile of rubble.

Castro's neighbours in the working-class district of Cleveland had vowed to see the house demolished at the conclusion of the trial.