The whereabouts are currently unknown of the man who leaked information about a top-secret U.S. surveillance program that monitors the telephone and Internet use of millions of people.
Edward Snowden, who worked as a contractor with the National Security Agency (NSA), was reported on June 10 to have checked out of his Hong Kong hotel.
The 29-year-old American has said he might try to seek asylum in Iceland.
In an interview in Hong Kong, Snowden said he leaked classified information about electronic surveillance programs to expose the truth and protect the basic privacy rights of people around the world.
Some U.S. lawmakers have demanded that Snowden be sent back to America to face charges.
The White House declined comment on the case June 10 but said an investigation is under way.
Based on reporting by Reuters, AP, and dpa