The former National Security Agency contractor who disclosed a highly classified surveillance program has had his U.S. passport revoked.

A U.S. official on Sunday said Edward Snowden's passport was annulled before he left Hong Kong for Russia. Snowden's travel plans could be complicated — but not thwarted — by a lack of passport. The U.S. official said that if a senior official in a country or airline ordered it, a country could overlook the withdrawn passport.

The former contractor is said to be in Moscow and his allies at anti-secrecy WikiLeaks say Snowden is bound for Ecuador. The foreign minister there says he has requested asylum.

The U.S. official would only discuss the passport on the condition of anonymity because the official was not authorized to discuss the matter.