Britain's leaders faced new pressure Saturday to explain any role they might have had in the release of the Lockerbie bomber after Libya's leader Muammar al-Qaddafi credited senior officials and members of the royal family for influencing the decision.

Britain has condemned the scenes of jubilation in Tripoli at the return of Abdel Baset al-Megrahi and has considered canceling a royal visit to Libya as a sign of displeasure.

But opposition leaders say comments from Gadhafi's son — who said the release was often brought up during trade talks — should be examined.

"It is very important, I think, for the reputation of our institutions of justice that it is made clear beyond any doubt that this was not connected with some political trade," David Lidington, the Conservative Party's spokesman on foreign affairs, told the BBC.

Thousands of young men greeted Megrahi's plane at a Tripoli airport Thursday night after he was released from a Scottish prison on compassionate grounds. Some threw flower petals as the 57-year-old former Libyan intelligence agent stepped from the jet.

British Foreign Secretary David Miliband on Friday condemned the scenes as "deeply distressing," He insisted any suggestion that the release was spurred by commercial interests was "a slur both on myself and on the government."

While Britain does have oil interests in Libya — notably a $900 million exploration deal between BP PLC and Libya's National Oil Co. — they are small compared to investments by Italy's Eni SpA.

Britain has walked a fine line — condemning Megrahi's reception without criticizing the decision to free him, which was made in Edinburgh under Scotland's separate judicial system.

Scottish Justice Secretary Kenny MacAskill made decision to release al-Megrahi on compassionate grounds because the Libyan has prostate cancer and was given only months to live by top British doctors. MacAskill said he rejected an option to release al-Megrahi under a prisoner transfer deal between Britain and Libya.

But pressure increased in London after Libyan television showed pictures of Gadhafi praising Prime Minister Gordon Brown, "the Queen of Britain, Elizabeth, and Prince Andrew, who all contributed to encouraging the Scottish government to take this historic and courageous decision, despite the obstacles."

A Buckingham Palace spokesman on Saturday said the release was "entirely a matter for the Scottish government." The official spoke on condition of anonymity in keeping with palace policy.

Megrahi is the only man convicted in the bombing of Pan Am Flight 103 over Lockerbie, Scotland. The explosion of a bomb hidden in the cargo hold killed all 259 people on the plane and 11 on the ground in Britain's worst terrorist attack.

Megrahi's trial at a special Scottish court set up in The Netherlands, which came after years of diplomatic maneuvering, was a step toward normalizing relations between the West and Libya, which spent years under U.N. and U.S. sanctions because of the Lockerbie bombing.