A TV screen shows a news report of Edward Snowden, a former National Security Agency contractor who leaked top-secret documents about sweeping U.S. surveillance programs, at a shopping mall in Hong Kong, June 22, 2013. (Kin Cheung/AP)

Obama administration officials Saturday publicly increased pressure on Hong Kong to move quickly to arrest Edward Snowden, a week after U.S. officials asked its government to detain the admitted leaker of documents about top-secret surveillance programs.

White House national security adviser Thomas E. Donilon said U.S. officials “are in conversation” with Hong Kong authorities and have asked the special administrative region of China not only to arrest the former National Security Agency contractor but also to extradite him to the United States to stand trial on criminal charges.

“If Hong Kong doesn’t act soon, it will complicate our bilateral relations and raise questions about Hong Kong’s commitment to the rule of law,” said another senior administration official, who spoke on the condition of anonymity because the official was not authorized to speak about an ongoing investigation.

The U.S. government, which has made the Snowden case a top priority and has devoted significant resources to prosecuting him, asked Hong Kong on June 14 to detain Snowden on a provisional arrest warrant. That same day, federal prosecutors filed sealed criminal charges against him, including theft, “unauthorized communication of national defense information” and “willful communication of classified communications intelligence information to an unauthorized person.”

The fact that the U.S. government asked Hong Kong to detain Snowden emerged Friday when The Washington Post disclosed the contents of the sealed criminal complaint.

The White House referred all questions to Justice Department officials, who declined to comment.

The reasons for the apparent lack of action by Hong Kong are unclear. Officials might still be looking for Snowden. The South China Morning Post reported Saturday that Snowden is not under police protection but is in a “safe place” in Hong Kong. The newspaper also reported that Snowden had revealed more details about U.S. surveillance of Hong Kong and China.

Under the extradition treaty between Hong Kong and the United States, a provisional warrant, as opposed to a regular one, is a faster way to detain suspected criminals because it does not require the initial approval of Hong Kong’s chief executive, currently Leung Chun-ying.

Instead, a judge can issue the warrant immediately. Simon Young, a legal professor at the University of Hong Kong, said a warrant for Snowden’s arrest could have been issued as early as June 14.

Leung’s office declined to comment on Snowden’s case Saturday. The police department did not respond to calls and e-mails.

Douglas McNabb, a criminal defense lawyer who specializes in international extradition cases, said that if authorities know Snowden’s location, he may already have asked for asylum, a complicated process that might have to be worked out before Hong Kong authorities could arrest him.

“If he applied for asylum, that process may trump being arrested on a provisional arrest warrant,” McNabb said.

Snowden, who turned 30 on Friday, revealed himself June 9 as the anonymous source for articles in the British newspaper the Guardian and The Post about the NSA surveillance of telephone calls and Internet communications. He was staying in an upscale hotel in Hong Kong, a city he said he had chosen because he felt he might win asylum there.

Snowden subsequently left the hotel, and it is unclear where he went. In a live Web chat Monday, he said he sees no possibility of a fair trial in the United States and suggested that he would try to elude authorities as long as possible.

Meanwhile, plans to protect Snowden appeared to be unfolding. Olafur Sigurvinsson, an Icelandic businessman, told reporters Thursday that he has a private jet ready to take Snowden to Iceland, which Snowden named in interviews as a potential haven.

KK Yuen, a spokesman for the Hong Kong Aviation Center, which handles private jet flights out of Hong Kong, declined to comment on whether Snowden or anyone on his behalf had made plans for him to fly out.

Snowden could have trouble leaving on a private jet without tipping off authorities. Yuen said that all passengers must go through immigration and customs checks.

If Snowden is arrested, he must be brought “as soon as practicable” before a Hong Kong judge, according to the extradition treaty. The judge would decide whether he should be removed from Hong Kong under the treaty terms.

Donilon said in an interview with CBS News that U.S. officials believe the charges against Snowden “present a good case for extradition” under the U.S. and Hong Kong Agreement for the Surrender of Fugitive Offenders.

“Hong Kong has been a historically good partner of the United States in law enforcement matters, and we expect them to comply with the treaty in this case,” Donilon said.

But Snowden can challenge any initial ruling to extradite him all the way to Hong Kong’s highest court, a process that could take months to run its course.

To fight extradition, Snowden could invoke Article 6 of the 1997 treaty, which states that a suspect will not be surrendered to face criminal prosecution for an offense of a “political character.”

Another unusual exception in the treaty could provide a defense for Snowden, according to extradition experts: Hong Kong authorities can refuse to surrender a suspect if extradition “implicates the defense, foreign affairs or essential public interest” of Hong Kong.

Regina Ip, a Hong Kong legislator and former security secretary, said Snowden will have plenty of defenders if he is arrested.

“I think if he stays in Hong Kong, there will be no lack of human rights lawyers who are happy to help him,” she said Saturday.

Last weekend, 200 to 300 protesters marched past the U.S. Consulate to support Snowden, applauding his release of the documents.

Hong Kong is in an unusual position in the matter because it has an independent legal system but must ultimately answer to the Chinese leadership in Beijing.

Yang reported from Hong Kong. Philip Rucker in Washington and Liu Liu in Beijing contributed to this report.