He arrived in Moscow on Sunday from Hong Kong, where he had been hiding since before the publication of articles relating to information he provided about classified US government programmes that collect phone records and online data.
Mr Snowden, 30, had been expected to fly to Cuba yesterday and then on to Ecuador.
But it appeared he had not yet left Moscow, where he was thought to be staying in an airport hotel. There was speculation that Russian intelligence officials may have taken the opportunity to question him over US espionage against Moscow, while other sources claimed he could have flown out unseen by waiting journalists at Sheremetyevo Airport.
Anti-secrecy organisation Wikileaks, which has taken credit for orchestrating Mr Snowden’s exit from Hong Kong, said it had approached Iceland and other countries with a formal request for asylum on behalf of the IT worker, who has been charged with espionage in the US after revealing details of internet and phone surveillance programmes by the US government’s National Security Agency.
“It is already public that I, as an Icelandic journalist, approached the Icelandic government with a formal request from Mr Snowden for asylum in Iceland,” Wikileaks spokesman Kristinn Hrafnsson said. “Similar processes were carried out elsewhere.”
Wikileaks founder Julian Assange – who has been living in Ecuador’s London embassy for the past year to avoid extradition to Sweden to face questioning on sex crime allegations – said he knew where Mr Snowden was, describing it as a “safe place”.
“The current status of Mr Snowden and Harrison is that both are healthy and safe and they are in contact with their legal teams,” Mr Assange said, referring to his former girlfriend Sarah Harrison, a Wiki-leaks representative who is accompanying Mr Snowden.
He said Mr Snowden’s “spirits are high”, but refused to reveal where he was.
US secretary of state John Kerry said it would be “deeply troubling” if Russia or Hong Kong had had adequate notice about Mr Snowden’s plans to flee to a country that would grant him asylum and still allowed him to leave.
He said it could affect relations between the countries. “There is a surrender treaty with Hong Kong and if there was adequate notice – I don’t know yet what the communication status was – but if there was, it would be very disappointing if he was wilfully allowed to board an airplane … and there would be, without any question, some effect and impact on the relationship and consequences. With respect to Russia, likewise,” Mr Kerry said.
Ecuador’s foreign minister, Ricardo Patino, said he was reviewing Mr Snowden’s asylum request and would make a decision based on human rights considerations. “We will consider the position of the US government and we will take a decision in due time in line with the [Ecuadorian] constitution, the laws, international politics and sovereignty,” he said.
It has been claimed Mr Snowden received refugee papers from the Ecuador government to secure him safe passage from Hong Kong.
Meanwhile, a petition asking President Barack Obama to pardon Mr Snowden has amassed 100,000 signatures in the US.
The petition, posted on Whitehouse.gov, refers to him as a “national hero” and says he should be pardoned immediately for any crimes he committed in “blowing the whistle”.