London Mayor Boris Johnson has said that if there was the "slightest evidence" that Libyan foreign minister Moussa Koussa was involved in the Lockerbie bombing, he should face trial. Koussa arrived in Britain on Wednesday and is said to have defected.
Prime Minister David Cameron said Mr Koussa's apparent defection told "a compelling story of the desperation and the fear at the very top of the crumbling and rotten Gaddafi regime".
He has also insisted that Mr Koussa had not been offered immunity from prosecution. Scottish prosecutors have asked to interview him about the 1988 Lockerbie bombing, which left 270 people dead, though government sources told the Guardian they did not think he was involved.
Watch more on the