The United Nations has released the text of a 1999 letter assuring the Libyan Government about the treatment of the two Lockerbie bombing suspects. The correspondence from UN Secretary General, Kofi Annan, contained pledges that the two men "will not be used to undermine the Libyan regime". But relatives of some of those who died in the tragedy are concerned that the letter pledged that no charges relating to the bombing would be brought against the Libyan leader, Colonel Gaddafi. The BBC's Matthew Cole reports: