He has returned to Moscow from Kirov, where a judge convicted him of embezzlement, in a case widely condemned as political.

The court ruled on Friday he could go back to Moscow until the appeal.

The jail term has been criticised by the US, EU and human rights groups.

Standing beside his wife Yulia, Navalny told a crowd of supporters at Yaroslavsky station on Saturday that "we are going to stand in the elections and we will win".

"We are a huge powerful force. We have taken away the Kremlin's privilege to put people in prison never to be seen again."

He was accepted as a candidate in the 8 September mayoral poll shortly before he was found guilty of embezzlement and there had been some doubt over whether he would run.

The anti-corruption activist said he would take part in campaigning for the election as long as it was possible.

A number of riot police were at the station and security forces were deployed in the surrounding area, Interfax news agency reports.

The BBC's Oleg Boldyrev who was there said it was a very upbeat start to an election campaign.

Hours after his conviction was announced in Kirov on Thursday, thousands of protesters took to the streets of Moscow in an unsanctioned demonstration, with reports of scuffles and dozens of people being detained.

President Vladimir Putin's spokesman Dmitry Peskov has since warned activists not to hold any more protests without official approval.,

Asked late on Friday whether there was any chance of Navalny being pardoned, Mr Peskov told reporters: "A convict first has to admit his guilt."

Navalny's release from custody in Kirov, 560 miles (900km) north-east of Moscow, had been sought by the prosecution as well as his defence.

The unexpected step was seen by some as an attempt to soothe public anger over a case that prompted Germany to question whether criminal justice was the main motive behind the trial. The US said it was "deeply disappointed and concerned" by the outcome.

Alexei Navalny, 37, rose to prominence before parliamentary elections in 2011, writing a blog in which he condemned the ruling United Russia party as "crooks and thieves".

The case brought against him in Kirov was that he led a group that embezzled timber worth 16m roubles ($500,000; £330,000) from the Kirovles state timber company while working as an adviser to governor Nikita Belykh.

Navalny will have to return to Kirov in a few weeks' time to appeal against the verdict.

With the conviction and appeal hanging over him, no-one can predict whether he will see the result of the elections as a free man, our correspondent says.