Former CIA employee Edward Snowden, who leaked details of US top-secret phone and internet surveillance, has disappeared from his hotel in Hong Kong.
Edward Snowden, 29, checked out from his hotel on Monday. His whereabouts are unknown, but he is believed to be still in Hong Kong.
Earlier, he said he had an “obligation to help free people from oppression”.
It emerged last week that US agencies were gathering millions of phone records and monitoring internet data.
A spokesman for the US Office of the Director of National Intelligence said the case had been referred to the Department of Justice as a criminal matter.
Meanwhile a petition posted on the White House website, calling for Edward Snowden’s immediate pardon, has gathered more than 30,000 signatures.
However, an opinion poll commissioned by the Washington Post suggests a majority of Americans think government monitoring of phone records is acceptable if the aim is to fight terrorism.
Hong Kong’s broadcaster RTHK said Edward Snowden checked out of the Mira hotel on Monday.
Reuters news agency quoted hotel staff as saying that he had left at noon.
Ewen MacAskill, a Guardian journalist, said he believed Edward Snowden was still in Hong Kong.
The Chinese territory has an extradition treaty with the US, although analysts say any attempts to bring Edward Snowden to America may take months and could be blocked by Beijing.
Edward Snowden was revealed as the source of the leaks at his own request by the UK’s Guardian newspaper.
He is believed to have arrived in Hong Kong on May 20. A standard visa on arrival in the territory for a US citizen lasts for 90 days.
His revelations have caused transatlantic political fallout, amid allegations that the UK’s electronic surveillance agency, GCHQ, used the US system to snoop on British citizens.
Foreign Secretary William Hague cancelled a trip to Washington to address the UK parliament on Monday and deny the claims.
Edward Snowden is described by the Guardian as an ex-CIA technical assistant, currently employed by Booz Allen Hamilton, a defense contractor for the US National Security Agency (NSA).