The release of Lockerbie bomber Abdelbaset al-Megrahi was “wrong and misguided”, British Foreign Secretary William Hague said in a letter to US senators today.
However, 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 British 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.
Megrahi's release on compassionate grounds came after medical evidence indicated he had three months to live - but next month will mark a year since he was freed.
The issue flared up again last week as Mr Cameron made his first official visit to the US, amid concern that the oil giant BP had lobbied the UK government over a proposed prisoner transfer deal with Libya.
Mr Hague says both he and British Prime Minister David Cameron had previously hit out at the decision to let Megrahi out.
“We think that the decision taken by the Scottish Executive to release him on compassionate grounds was wrong and misguided,” Mr Hague states.
“Notwithstanding that, however, we must also recognise that it was legally and constitutionally proper that the decision over his release was one for the Scottish Executive alone to take.”
The Scottish Government had wanted anyone convicted of the Lockerbie bombing excluded from a controversial prisoner transfer deal agreed with Libya in 2007. But this condition was opposed by the Libyans and the UK Government eventually agreed to the PTA without exclusions.
Mr Hague’s letter today says a number of conversations took place between the UK Government and BP about the exclusion.
“There were three discussions between BP and Mr Jack Straw or his office between October and November 2007 and at least two contacts in the same period between BP and the Prime Minister’s foreign policy adviser,” his letter states.
BP had been made aware by the Libyans that failure to agree a PTA could damage an exploration deal it had signed with the African country, Mr Hague says, and the oil giant wanted to bring this to the UK Government’s attention.
Mr Hague insisted this was “perfectly normal and legitimate practice” for a British firm.
Scottish justice secretary Kenny MacAskill, who took the decision to release Megrahi, rejected a request from Libya on prisoner transfer.
Mr Hague added: “There is no evidence that corroborates in any way the allegation of BP’s involvement in the Scottish Executive’s entirely separate decision to release him on compassionate grounds in 2009, nor any suggestion that the Scottish Executive decided to release him on compassionate grounds in order to facilitate oil deals for BP.”