Russian President Vladimir Putin has described US intelligence leaker Edward Snowden as " a free man," confirming that he is still in a Moscow airport transit zone and rejecting calls for his extradition to the United States.

In his first comments about the chase for Snowden that has captivated world attention, Putin on Tuesday said the former CIA agent's arrival in Moscow from Hong Kong was "completely unexpected" for the Russian authorities.

The dramatic announcement ended two days of guessing over the whereabouts of the fugitive, who leaked revelations of massive US surveillance programmes to the media and is now wanted by Washington.

"It is true that Mr. Snowden came to Moscow," Putin said at a news conference while on a visit to Finland. "For us, this was completely unexpected."

"He arrived as a transit passenger and he does not need a visa or other documents. He can buy a ticket and go wherever he pleases. He did not cross the state border, as a transit passenger he is still in the transit hall," Putin added.

Snowden had been expected to board a flight for Cuba on Monday, reportedly on his way to seek asylum in Ecuador. But he never did and Putin appeared to confirm that he was still uncertain over his onward travel plans.

"Mr. Snowden is a free man, the sooner he selects his final destination point, the better for us and for himself," he said.

--- 'A lot of squealing and not much wool' ---

The US has urged Russia to use all means to expel Snowden, who reportedly arrived at Moscow's Sheremetyevo airport on a flight from Hong Kong on Sunday, infuriating the US which had issued a request for his arrest in the southern Chinese city.

However Putin insisted that Russia only extradites foreign nationals to countries with which it has a formal extradition treaty.

"We have no such agreement with the United States," he said, calling US allegations that Russia is breaking the law "nonsense and rubbish."

White House National Security spokeswoman Caitlin Hayden later told AFP that: "While we do not have an extradition treaty with Russia, there is nonetheless a clear legal basis to expel Mr. Snowden."

Putin said he would personally prefer not to deal with cases such as those of Snowden and WikiLeaks founder Julian Assange, who is holed up in Ecuador's embassy in London to avoid charges of sexual assault in Sweden.

"It's the same as shearing a piglet: there's a lot of squealing and not much wool," he said.

WikiLeaks responded by thanking Putin on its Twitter account: "We appreciate President Putin's supportive comments on Assange and Snowden," it said.

The group also suggested that the US by "cancelling Snowden's passport and bullying intermediary countries may keep Snowden permanently in Russia."

Speaking in Jeddah, US Secretary of State John Kerry called for Russia to be "calm" and hand over Snowden, saying Washington was not looking for "confrontation."

The dispute over the 30-year-old former National Security Agency (NSA) technician risks sharpening tensions between Washington and Moscow as well as Beijing at a time when they are struggling to overcome differences to end the conflict in Syria.

Transit rules on the website of Sheremetyevo airport stipulate that "foreign citizens can remain in the airport up to 24 hours without a Russian visa" and must have a ticket to their next destination. No Russian official has commented on this issue in Snowden's case.

--- 'Groundless and unacceptable' ---

Snowden had been expected to travel on with the state carrier Aeroflot on Monday to Havana, but never appeared on the flight, sending dozens of journalists on a fruitless 10-hour plane ride.

There have been no sightings of Snowden in the airport, located north-west of Moscow, despite many film crews stationed there.

The leftist Latin American state of Ecuador has said it was considering a request he made for asylum and Assange said Snowden was "safe" after leaving Hong Kong with a refugee document supplied by Ecuador.

On Tuesday Venezuela's President Nicolas Maduro also said he would consider an asylum request from Snowden.

"We have not received an official request. But in the event we were to receive one, we would evaluate it as we understand Ecuador is doing," Maduro said during an official visit to Haiti.

Snowden abandoned his high-paying intelligence contractor job in Hawaii and went to Hong Kong on May 20 to begin issuing a series of leaks on the NSA gathering of phone call logs and Internet data, triggering concern from governments around the world.

Hong Kong, a special administrative region under Chinese rule that has maintained its own British-derived legal system, said the US government request to arrest him did not fully comply with Hong Kong legal requirements.

But White House spokesman Jay Carney lashed out at Beijing over its purported role in the affair, saying China's failure to "honour extradition obligations" had dealt a "serious setback" to efforts to build trust with new President Xi Jinping.

Meanwhile Snowden told the South China Morning Post in a story published Tuesday that he joined contractor Booz Allen Hamilton, from which he stole secrets on NSA surveillance programs, specially to gain access to sensitive information and spill it to the press.

ma-zak-sjw-am/pvh/sls