The Federal Migration Service confirmed he had completed the relevant paperwork at Moscow's Sheremetyevo airport, where he has been for the past three weeks.

Mr Snowden is wanted by the US for leaking details of government surveillance programmes.

He has no travel documents so has been unable to take up asylum offers from a number of Latin American states.

"He reached the conclusion that he needs to write an application for temporary asylum, and this procedure has just been done," said Anatoly Kucherena, a lawyer with strong links with the Kremlin who helped Mr Snowden with the paperwork.

"For now he is not going to go anywhere. For now he plans to stay in Russia," he said.

Mr Kucherena said the fugitive had stated in the application that he faced possible torture and execution if he returned to the US.

If his application is accepted, he will be free to work and move freely in Russia, said the lawyer.

Russia's Interfax news agency quoted Mr Kucherena as saying he had asked Mr Snowden whether he would observe a request from President Vladimir Putin to not harm US interests if he is able to leave the airport.

"He replied: 'I will observe this condition'," Mr Kucherena told the agency.

A presidential spokesman told Interfax that Mr Putin had not yet reacted to the asylum request, and that the decision on whether it would be granted was not his to make.

Interfax also quoted a migration service official as saying that the application had to be considered within three months.

Officials said Mr Snowden might be moved to a facility in the airport for accommodating refugees while his application was processed.

'Not Putin's decision'

Mr Snowden arrived in Russia on 23 June, having left Hong Kong, from where he had issued his leaks to the media.

He held a news conference at the airport on 12 July, where he said he was seeking asylum in Russia.

He has sent requests for political asylum to at least 21 countries, most of which have turned down his request. However, Bolivia, Nicaragua and Venezuela have indicated they could take him in.

But he is unable to leave the transit zone as he currently has no asylum documents or Russian visa, and the US has revoked his passport.

Some European countries are likely to close their airspace to any plane suspected of carrying the fugitive.

Mr Snowden's leaking of thousands of classified US intelligence documents has led to revelations that the National Security Agency is systematically seizing vast amounts of phone and web data.

The documents have also indicated that both the UK and French intelligence agencies allegedly run similarly vast data collection operations, and the US has been eavesdropping on official EU communications.