Update | Snowden still stuck at Moscow airport after permit mix-up

Fugitive whistle-blower Edward Snowden's hopes of leaving Moscow's Sheremetyevo Airport for the first time in a month yesterday were dashed when he failed to secure permission from Russia to leave.

An airport source said the former security agency contractor - wanted by the United States for revealing details of government intelligence programmes - was handed documents by his lawyer which were expected to include a pass to leave the transit area.

But Snowden did not go through passport control and lawyer Anatoly Kucherena, who is assisting him with his request for temporary asylum in Russia, said he did not have the pass he needed.

It was not clear whether there had been a last-minute political intervention or hitch, but Kucherena said he hoped Snowden's status would be resolved soon.

In Washington, the White House said it was seeking clarification of his status. Russia's RIA Novosti news agency earlier quoted an unidentified security official as saying that Snowden was given the document, allowing him to formally enter Russia. Kucherena denied this. "As of today, this document has not yet been given [to him]," he said.

A large crowd of media representatives gathered outside a door marked "Staff only" on the lower floor of Terminal E at Sheremetyevo after the Russian agency report, with police and security guards on patrol.