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 al-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 al-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.