GORDON Brown's government could have used its powers under the Scotland Act to challenge the decision to release the Lockerbie bomber, it has emerged.
Scottish Secretary Jim Murphy could have overruled Scottish justice secretary Kenny MacAskill and stopped the release of Abdelbaset Ali Mohmed al-Megrahi if the case was deemed to have breached "international obligations".
Senior diplomats have insisted there was a "clear understanding" between the UK and the US that Megrahi would serve out his sentence in Scotland. The US Justice and State departments have also insisted they had been given assurances in the 1990s that Megrahi would remain imprisoned under Scottish jurisdiction.
The disclosure angered the families of American victims of the bombing yesterday and fuelled resentment at the way in which the UK government distanced itself from the decision to release Megrahi on compassionate grounds, arguing it was a matter solely for Scottish ministers and the Scottish judiciary.
Andrew Mackinlay, a senior Labour MP, has now argued for the Scotland Act to be tightened to allow Westminster to override Scottish Government decisions if they have foreign policy implications for the whole of the UK. "Since there appears to be a provision in the Scotland Act, it should at least have been examined," he said.
"It is inconceivable that a Labour secretary of state or (UK] government ministers, including the Prime Minister or Foreign Secretary, would not have looked at this or at least asked the Attorney General for advice. Jim Murphy needs to answer why he did not use this provision."
The key part of the Scotland Act says: "If the Secretary of State has reasonable grounds to believe that any action proposed to be taken by a member of the Scottish Executive would be incompatible with any international obligations, he may by order direct that the proposed action shall not be taken."
It goes on to say Scottish laws can be revoked if "the Secretary of State has reasonable grounds to believe (it] to be incompatible with any international obligations or the interests of defence or national security".
Mackinlay, who serves on the foreign affairs committee that is launching an investigation into US-UK relations and the impact of the Lockerbie decision, has also called for the Scotland Act to give Westminster the final say on any decisions affecting foreign policy.
"There should be a double lock on issues of national security and foreign policy," he said. "It would be inconceivable for such a decision to be taken by federal governments in the US, Canada, Germany or Australia."
Frank Duggan, president of Victims of Pan Am Flight 103 and a Washington-based lawyer, said: "I didn't know there was a provision like that. I just wish that the British government had used it to overturn the decision, which caused us so much grief. But it is clear that the British government just didn't want to do that."
However, a spokesman for Murphy dismissed suggestions that he could have intervened: "There were no national security implications (in Megrahi's release]. It was entirely a matter for Scottish ministers.
"There was no power for the Scottish Secretary to stop Scottish ministers making these decisions. Devolution gives the Scottish Government the right to take decisions and it is within their rights to take the wrong decisions."
He added that there were no international obligations and no defence implications either from releasing Megrahi. But Sir Christopher Meyer, who was ambassador to the US at the time of the Lockerbie bombing, last night said there was a "clear understanding" that Megrahi would serve his full sentence in Scotland.
"I thought the right thing to do was to let him fight his appeal in court, and the fact that he may have died was beside the point," Meyer said.
Megrahi, the only man convicted of the Lockerbie bombing in 1988 in which 270 people died, was released last month from Greenock Prison on the grounds that he is suffering from prostate cancer and only has weeks to live.
But his release has been followed by bitter argument, including over Westminster's reluctance to get involved. Last week, former Labour first minister Jack McConnell said the UK and Holyrood governments should have discussed the release because of the wide- ranging ramifications.