The release of Lockerbie bomber Abdelbaset al-Megrahi was "wrong and misguided", Foreign Secretary William Hague has said in a letter to US senators.
But he accepted it was "legally and constitutionally proper" that the decision was one for the Scottish Government.
Mr Hague also said several discussions were held between then foreign secretary Jack Straw and oil giant BP ahead of a controversial prisoner transfer agreement being agreed with Libya in 2007.
Meghrahi is the only person convicted of the 1988 bombing which killed 270 people and his release on compassionate grounds last August prompted anger in the US.
Mr Hague's letter was sent to Senator John Kerry, who chairs the Senate Foreign Relations Committee which is holding an inquiry into the bomber's release.