A top Russian politician has declared it would be "morally impermissible" to hand fugitive intelligence leaker Edward Snowden over to the United States.

Snowden, the 30-year-old former contractor for the National Security Agency (NSA), remains in a political limbo at a Moscow airport.

He has been living in the transit zone of Sheremetyevo airport for over a week, unable to fly on with a revoked US passport or exit the airport without a Russian visa.

Snowden has requested asylum in Ecuador but is unable to get to its embassy in central Moscow.

Alexei Pushkov, who heads the international affairs committee at the Duma lower house of parliament, said it would be wrong to give Snowden over to the United States, where he is wanted for leaking classified information about covert US surveillance programs.

"It's not a matter of [Snowden's] usefulness [to Russia] - it's a matter of principle," he wrote on Twitter on Sunday.

"Handing over a political refugee is morally impermissible."

The Kremlin on Sunday played down the fact that Snowden is still living at the airport, with a spokesman for president Vladimir Putin telling the Echo of Moscow radio station that "this issue is not on the Kremlin's agenda."

"Since it's not our issue, I don't know what options there are for the situation's development, nor what the legal or other aspects are in this," said spokesman Dmitry Peskov.

Mr Putin shockingly admitted on Tuesday that Snowden is staying in the transit zone of Sheremetyevo airport, and cannot be extradited to the US due to the lack of a bilateral extradition agreement.

The Russian leader also advised Snowden to pick his destination soon.

The situation seems to be near a dead end as Ecuador has declared that it is up to Moscow to resolve the dilemma over Snowden.

"To process the asylum application, [Snowden] must be in Ecuadoran territory," president Rafael Correa said late Saturday.

However, Snowden would need a visa from Russian authorities to get to Ecuador's embassy in central Moscow.

"We cannot be on the sidelines; we should participate in his fate," said another Russian senator, Valery Shnyakin, who is the deputy chairman of the international affairs committee in the Federation Council upper house of parliament.

"We should calculate the negative repercussions on our relations with the Americans," he added in remarks posted on the ruling United Russia party website. "For that, we need some kind of negotiations and meetings."

Reuters