Ambassador Nigel Sheinwald says his government "deeply regrets" the anguish that Abdel Baset al-Megrahi's release caused the families of the bombings' victims on both sides of the Atlantic.
But in an open letter to U.S. Sen. John Kerry published Friday, Sheinwald defended oil company BP from claims that it pressed to have al-Megrahi released.
Kerry and others have revived the controversy over the 2007 deal which awarded BP a major oil exploration contract - and raised the prospect that al-Megrahi would be freed.
The senators have called for an investigation into BP's lobbying for the pact.
