Libya said it had demanded an explanation from Washington on Sunday for the "kidnap" of a citizen in an unauthorised commando raid on its territory that netted a top al Qaeda suspect.
"The Libyan government has been following the reports of the kidnap of one of the Libyan citizens wanted by the authorities in the United States," a government statement said.
"As soon as it heard the reports, the Libyan government contacted the US authorities to demand an explanation."
US special forces seized Abu Anas al-Libi in a commando raid in broad daylight on Saturday, sealing a 15-year manhunt for the top al Qaeda suspect.
A source close to Libi said he was snatched by armed men in Tripoli.
Libi, who was on the FBI's most wanted list with a $5 million reward, was indicted in US federal court in New York for allegedly playing a key role in deadly 1998 bombings of US embassies in Kenya and Tanzania.
"As the result of a US counterterrorism operation, Abu Anas al-Libi is currently lawfully detained by the US military in a secure location outside of Libya," Pentagon spokesman George Little said in a statement.