US whistleblower Edward Snowden has been meeting human rights groups at Moscow airport to discuss what he called threatening and illegal behaviour by the United States to prevent him gaining asylum, according to the Guardian website.

Earlier on Friday, in a letter sent to a Human Rights Watch official, the former intelligence agency contractor said that he had invited human rights groups to meet at Russia's Sheremetyevo Airport where he has been holed up since he flew to Moscow from Hong Kong last month.

Al Jazeera’s Peter Sharp, reporting from Moscow, said he had spoken to one of the Russian lawyers invited to the meeting, who believed Snowden would ask for a second time for political asylum to Russia.

"There is a long list of invitees," Sharp said. "Amnesty International, Human Rights Watch, the UN Representative to the Russian Federation and the Deputy Speaker of the Duma."

Kremlin representatives have said they have not been invited.

"Asked if they would attend if they were, a spokesman went out on the line of the last couple of weeks; ‘This is not our business, he’s on his own’," our correspondent said.  

'Could face ill-treatment'

Sergei Nikitin, head of Amnesty International’s Russia office, told The Associated Press that he planned to meet Snowden. The organisation also confirmed their attendance on their website.

"In Amnesty International, we believe that Snowden could face ill-treatment if extradited to the United States," the group said.

"Nobody, regardless of the country they are in, should be extradited before their asylum application has been considered."

Venezuela, Nicaragua and Bolivia have said they would be willing to grant asylum to Snowden.

However, it is unclear if Snowden could fly from Moscow to any of the Latin American countries without passing through the airspace of the US or allied countries.

In his letter, Snowden said "The scale of threatening behaviour is without precedent: never before in history have states conspired to force to the ground a sovereign president's plane to effect a search for a political refugee", referring to the denial of airspace by a number of European countries to Bolivian President Evo Morales.

Spain had said on Wednesday it was asked to do so by the US.

Snowden had made an earlier application for Russian asylum, but Russian President Vladimir Putin said asylum would be conditional on Snowden stopping leaking US secrets. Snowden then withdrew his asylum bid, Russian officials said.

Source: Al Jazeera and agencies