Updated

US intelligence leaker Edward Snowden won support from Cuba for his bid to seek asylum in Latin America as he began his third week in limbo at a Moscow airport on Monday.

Cuba, a key transit point from Russia on the way to Latin America, supported the leaders of Bolivia, Venezuela and Nicaragua, who have offered the 30-year-old fugitive a possible lifeline as he remains marooned without documents in the transit area of a Moscow airport.

"We support the sovereign rights of the Bolivarian Republic of Venezuela and all the regional states to grant asylum to those who are being persecuted for their ideals or their fight for democratic rights, in accordance with our traditions," Cuban leader Raul Castro said on Sunday.

Speaking to Cuba's national assembly, Castro did not say whether his country, which has been showing signs of mending ties with Washington, would itself offer refuge to Snowden.

"If Raul Castro's solidarity on #Snowden is serious, Cuba will publicly offer Snowden asylum," anti-secrecy organisation WikiLeaks said on Twitter.

Multiple obstacles continue to cloud the former National Security Agency contractor's asylum hopes however and it remains unclear how he would be able to leave Russia, even if granted asylum by the three Latin American countries.

On Monday, the Moscow embassies of Bolivia, Venezuela and Nicaragua said they were unaware of any developments that would help Snowden escape Sheremetyevo Airport.

"We do not have any information, no one turned to us," a representative of the Venezuelan embassy in Moscow told AFP. Spokespeople for the Bolivian and Nicaraguan embassies also said they did not have any information.

The Kremlin indicated it wanted to keep the Snowden affair at arm's length, declining to say how the US leaker could leave without a valid passport.

"That's not our business," President Vladimir Putin's spokesman Dmitry Peskov told AFP. "We are not saying anything."

Snowden, who is seeking to evade US justice for leaking explosive details about a vast US electronic surveillance programme, caught the Kremlin off guard when he arrived in Russia from Hong Kong on June 23.

After the United States revoked his passport, Snowden, who applied for asylum in 27 countries, has been unable to leave the Sheremetyevo transit zone.

The only flight for which Snowden was known to have been checked-in -- a 12-hour Aeroflot flight to Havana -- left on June 24 without the fugitive but with several dozen journalists on board.

The Kremlin has been forced to perform a tough balancing act, saying it would not expel the US national but also stressing it did not want to damage ties with Washington ahead of Putin's summit with US leader Barack Obama in early September.

On Monday, the Kommersant daily, citing a source close to the US State Department, said Obama was unlikely to come to Moscow if Snowden was still stuck in the airport.

Peskov dismissed the report as "speculation".

Even if Snowden receives a new passport or travel document and manages to board a flight to Latin America, there are no guarantees that his plane would not be grounded once it reaches European airspace, analysts say.

Putin said Snowden could remain in Russia as long as he stopped his leaks, a condition the Kremlin later said the American was not willing to honour.

"Bolivia and Venezuela, with their unstable governments, cannot guarantee him anything," said security analyst Pavel Felgenhauer.

He said Snowden was increasingly vulnerable to pressure from Russian special services who he said may strong-arm him into remaining in Russia and cooperating.

Highlighting the increasingly absurd situation Snowden finds himself in, sultry ex-spy Anna Chapman proposed marriage to him in a bizarre turn of events that unleashed a torrent of witty comments in Russia last week.