Libyan Prime Minister Ali Zeidan was kidnapped from his Tripoli hotel at dawn on Thursday by an armed group and taken to an unknown location, the government and sources said.
"The head of the transitional government, Ali Zeidan, was taken to an unknown destination for unknown reasons by a group" of men believed to be former rebels, the government said in a brief statement on its website.
A source in the prime minister's office said Zeidan had been kidnapped from Tripoli's Corinthia hotel, where he resides.
The abduction comes five days after US commandos seized senior Qaeda figure Abu Anas al-Libi -- indicted for the twin 1998 bombings of US embassies in east Africa -- off the streets of Tripoli and whisked him away to a warship.
The government said it suspected two groups of ex-rebels, the chamber of revolutionaries and the brigade for the fight against crime, which in principle fall under the defence and interior ministries, of being behind the kidnapping.
The cabinet and the General National Congress, Libya's top political authority, were dealing with the situation the statement said, while calling on citizens to remain calm.
Saturday's raid by US commandos in Tripoli has embarrassed and put the Libyan government under pressure from its critics -- in particular some former rebel groups in the 2011 revolt that ousted and killed dictator Moamer Kadhafi.