US President Barack Obama says an alleged al-Qaeda operative snatched by US commandos in Libya was involved in plots that killed hundreds of people and will be brought to justice.
Obama was speaking just hours after Libya demanded Washington "immediately" hand back Anas al-Libi, claiming his capture was a flagrant violation of the country's sovereignty.
Vowing that America will continue to hunt down regional terror groups, Obama told reporters on Tuesday that Libi "helped plan and execute plots that killed hundreds of people, a whole lot of Americans. We have strong evidence of that. And he will be brought to justice".
Libya is bristling after the US commandos snatched Libi, a Libyan citizen, from his car on a Tripoli street in broad daylight on Saturday.
The government summoned the US ambassador and Prime Minister Ali Zeidan insisted all Libyans should be tried on home soil.
The case has embarrassed the Libyan government and put it under pressure from its critics - notably former rebel groups in the 2011 revolt that ousted dictator Muammar Gaddafi.
The General National Congress stressed "the need for the immediate surrender" of Libi, and described the US operation as a "flagrant violation" of Libya's sovereignty.
The text also called for the "need to allow the Libyan authorities and their families to get in touch with him (Libi) and guarantee them access to a lawyer."
It was the first official statement from Libya that clearly condemned the operation.
Libi - whose real name is Nazih Abdul Hamed al-Raghie - was on the FBI's most wanted list with a $US5 million ($A5.32 million) (3.7 million euro) bounty on his head for his alleged role in the 1998 twin bombings of two US embassies in East Africa.
He is reportedly being held aboard a US naval ship in the Mediterranean.
The justice minister summoned US ambassador Deborah Jones to answer questions about the operation.
"Salah al-Marghani summoned the ambassador of the United States on Monday morning to ask for answers to several questions relating to the case" of Libi's capture, his ministry said.
"We insist that Libyan citizens must be tried in Libya, and Libya will not deliver its citizens abroad for trial," he said.
Obama has refused to answer a question at a White House news conference on whether he believed Libi's capture inside Libya was in accordance with international law.
He defended US actions though, saying that in parts of Africa radical groups could mobilise because of "the lack of capacity on the part of the governments, in some cases because it is easier for folks to hide out in vast terrains that are sparsely populated."
"We're going to have to continue to go after them," said the US commander-in-chief.
Amnesty International has sharply criticised Libi's capture, saying it violated "fundamental human rights principles".
