The ability of contractor-turned-fugitive Edward Snowden to evade arrest is raising new concerns among U.S. officials about the security of top-secret documents he is believed to have in his possession — and about the possibility that he could willingly share them with those who assist his escape.

It's unclear whether officials in Hong Kong or in Russia, where Snowden fled over the weekend, obtained any of the classified material. A spokesman for the anti-secrecy group WikiLeaks, which has been assisting the former National Security Agency contractor, strenuously denied reports that foreign governments had made copies of the documents.

"This rumor that is being spread is a fabrication and just plays into the propaganda by the administration here that somehow Mr. Snowden is cooperating with Russian or Chinese authorities," spokesman Kristinn Hrafnsson said Monday.