Edward Snowden, the former US intelligence contractor who leaked classified documents revealing US internet and phone surveillance, has asked Ecuador for asylum.
The request was confirmed by Ecuador's foreign minister on Twitter.
Mr Snowden had fled the US for Hong Kong but flew out on Sunday morning and is currently in Moscow.
A US extradition request to Hong Kong failed but Washington insists he should now be denied international travel.
The US justice department has called Hong Kong's decision not to arrest Mr Snowden "troubling".
On Sunday, a US official said Washington had contacted "Western Hemisphere" nations that Mr Snowden might travel to, or through.
"The US is advising these governments that Snowden is wanted on felony charges, and as such should not be allowed to proceed in any further international travel, other than is necessary to return him to the United States," the state department official said.
Earlier, Ecuador's Foreign Minister Ricardo Patino, who is in Vietnam, said on Twitter: "The Government of Ecuador has received an asylum request from Edward J. #Snowden."
Wikileaks said in a statement that Mr Snowden was "bound for the Republic of Ecuador via a safe route for the purposes of asylum, and is being escorted by diplomats and legal advisers from Wikileaks".
Ecuador is already giving political asylum to Wikileaks founder Julian Assange, who has been sheltering in its London embassy for the past year.
The anti-secrecy group said Mr Snowden's asylum request would be formally processed when he arrived in Ecuador.
Spokesman Kristinn Hrafnsson told the BBC he believed history would show that the former analyst had performed "a great public service".
The US state department said Mr Snowden's passport had been revoked, saying this was "routine and consistent with US regulations".
However, one US official told the Associated Press that if a senior official in a country or airline ordered it, a country could overlook the lack of a passport.
Hong Kong officials said Mr Snowden had left "on his own accord for a third country through a lawful and normal channel" because the US extradition request was incomplete and there was no legal basis to restrict him from departing.
The US justice department said it was "disappointed" that Hong Kong did not arrest Mr Snowden and that it "disagrees" with its reasons for not doing so.
An official said that at no point during talks on Friday did Hong Kong raise issues regarding the sufficiency of the US request.
"In light of this, we find their decision to be particularly troubling," the official said.
Mr Snowden left on Aeroflot flight SU213 and landed at Moscow's Sheremetyevo Airport shortly after 17:00 local time (13:00 GMT) on Sunday, where he was reportedly picked up by either a Venezuelan or Ecuadorean embassy car.
Reports suggest he will fly out of Russia on an early afternoon flight to the Cuban capital Havana, where he is booked on another flight to Caracas, Venezuela.
Following that route would enable him to fly on to Ecuador without risk of arrest by US authorities.
It is unclear where Mr Snowden currently is, but he is reported to have not left the airport, and the Ecuadorean ambassador was spotted at an airside hotel.
The US and Ecuador have a joint extradition treaty, but it is not applicable to "crimes or offences of a political character".
The US justice department has said it will seek co-operation from whichever country Mr Snowden arrives in.
But if Mr Snowden ends up in Ecuador, it is going to be extremely difficult for the Americans to get him, the BBC's Paul Adams in Washington reports.
Mr Snowden had left his home in Hawaii after leaking details of his work as an NSA (National Security Agency) analyst and the extensive US surveillance programme to the UK's Guardian newspaper and the Washington Post.
He has been charged in the US with theft of government property, unauthorised communication of national defence information and wilful communication of classified communications intelligence.
Each of the charges carries a maximum 10-year prison sentence. The complaint is dated 14 June - although it was made public only on Friday.
NSA chief Keith Alexander told ABC News on Sunday there had been no warning that Mr Snowden had taken the documents.
"Clearly, the system did not work as it should have," he said.
Gen Alexander also said the spying agency was overhauling its operations to tighten security on contractors.
The leaks have led to revelations that the US is systematically seizing vast amounts of phone and web data under an NSA programme known as Prism.
Mr Snowden said earlier that he had decided to speak out after observing "a continuing litany of lies" from senior officials to Congress.
US officials have defended the practice of gathering telephone and internet data from private users around the world.
They say Prism cannot be used to intentionally target any Americans or anyone in the US, and that it is supervised by judges.