Libya's foreign minister Moussa Koussa has fled to London to seek refuge after quitting the government in protest against attacks on civilians by leader Muammar Gaddafi's forces.
Several thousand people have been killed and thousands wounded since the uprising against the Gaddafi regime began six weeks ago.
Western forces led by the United States, France and Britain began air attacks on government troops on 19 March in order to enforce a United-Nations-sanctioned no-fly zone and protect civilians. NATO assumed responsibility for the military operation earlier this week.
The BBC reports Mr Koussa flew in from Tunisia on a non-commercial flight to an airport near London, saying he was no longer willing to represent the Gaddafi government.
The British foreign office is trying to determine whether he wants to defect, and has questioned him for several hours.
Mr Koussa was one of Gaddafi's key officials and the architect of a dramatic shift in Libya's foreign policy that brought the country back to the international community after years of sanctions.
Earlier, British foreign secretary William Hague announced that five Libyan diplomats were being expelled from Britain because they could "pose a threat" to the nation's security.
