The National Security Agency Contractor, Edwards Snowden, who leaked secret U.S. documents, has gone missing in Hong Kong since Monday. His disappearance comes in the wake of a possible extradition demand by the Obama administration.

Snowden checked out of his hotel Monday morning, according to sources and has been untraceable since then.

Snowden revealed to the media NSA's program of monitoring phone calls and internet activities of millions of people. The government agency accessed data of major internet companies. The 29-year-old Snowden said that he leaked the information to protect the "basic liberties" of people across the world.

Former head of Hong Kong's  security department, Regina Ip Lau Suk-yee, advised Snowden to leave the city as the administration was obliged to comply with the terms of agreements'' with the US government, which included the extradition of fugitives, AFP reports.

"If Mr Snowden is in Hong Kong and if the US justice department decides to initiate criminal investigation and if the offence comes in the purview of our agreement, they could through the US consulate ask our law enforcement agencies to assist in locating him ... and possibly even arresting him," said Regina Ip.

"He may not have known that the US has signed treaties with us ... so it's best he leave," she said.

However, Snowden's disclosure has garnered him some worldwide support. There are many people in Hong Kong who want the government to support him. In New York, a rally was organized by sympathizers and an online pardon petition has also been launched.

"He faces a very difficult situation now," said Janine Gibson, Editor-in-Chief Guardian, United States. "He's expressed that he would like, perhaps, to be given asylum in somewhere like Iceland which has an excellent track record on freedom of information. And perhaps that will come out for him. Clearly we wouldn't want to see him come to any harm."