Prime Minister Gordon Brown today insisted there had been "no double-dealing" by UK ministers over the release of the Lockerbie bomber.
His comments came as Foreign Secretary David Miliband confirmed Libya was told earlier this year that the Prime Minister did not want to see Abdelbaset Ali Mohmed Al Megrahi die in a Scottish jail.
Conservative leader David Cameron called for an independent inquiry into the controversy, accusing Mr Brown of not being "straight" with the public about the Government's approach.
Libyan officials today said Megrahi, convicted of the bombing of PanAm flight 103 which killed 270 in 1988, had been moved into intensive care at a Tripoli hospital and was "in a bad way".
Mr Brown has faced mounting criticism in the fortnight since the bomber's return to Libya for his failure to say whether he agreed with the Scottish Government's decision to release him on compassionate grounds due to his terminal cancer.
He today sought to draw a line under the affair, insisting that he had given no assurances on Megrahi's future to Libyan leader Muammar Gaddafi.
The final decision to free the bomber was taken by the Scottish Government and UK ministers did not seek to influence it, he said.
"There was no conspiracy, no cover-up, no double-dealing, no deal on oil, no attempt to instruct Scottish ministers, no private assurances by me to Colonel Gaddafi," Mr Brown told an audience in Birmingham.
Denying claims Megrahi's release was intended to smooth trade and oil deals with the north African state, the PM added: "There was never a linkage between any other issue and the Scottish Government's decision about Megrahi's future.
"Our interest throughout has been to strengthen the coalition against international terrorism."
Mr Miliband this morning confirmed former Foreign Office minister Bill Rammell was speaking on his behalf when he told Libya earlier this year that neither the Foreign Secretary nor Mr Brown wanted Megrahi to die in jail.
The Foreign Secretary told BBC Radio 4's Today programme: "We did not want him to die in prison, no, we weren't seeking his death in prison."
Mr Brown stopped short of confirming explicitly that he had favoured releasing Megrahi before his death.
But he said: "Did we as a Government say we would try to stop the Scottish Executive and force Megrahi to die in prison? No, we did not do so, and did not have the power to do so - and that was the right thing to do."
Mr Cameron said that the PM was "quite wrong" to claim there had been no double-dealing.
"We learnt this morning from the Foreign Secretary that a Government minister told the Libyans that the PM and Foreign Secretary did not want Mr Megrahi to die in a Scottish jail," said the Tory leader.
"But at the same time we know the Government was giving assurances to the United States that Mr Megrahi would spend his full sentence in a Scottish prison. So that is double-dealing.
"But almost more serious is the double-dealing with the British public, where on the one hand Gordon Brown has completely refused to give his opinion on the release of this mass murderer, but on the other hand was content for the Libyans to be told that he shouldn't die in prison. That is double-dealing.
"The PM has got to be straight with people, answer the questions that need to be answered and set up an inquiry so we can sort out this mess once and for all."
Mr Brown described the scenes accompanying the bomber's return on August 20 as "despicable".
But the PM took credit for the fact that Megrahi did not appear personally at last night's celebrations in Tripoli marking Col Gaddafi's 40 years in power, which instead featured a video of Megrahi being feted on his arrival at the airport.
"Would it have been right to have spoken publicly about the issue before the decision when it was a matter for the Scottish Government? No, we would have been wrong to intervene when it was a quasi-judicial decision for the Scottish Government," said Mr Brown.
"After the decision was made, and after the despicable scenes at Tripoli airport, was I right to use my energies to minimise further unnecessary suffering for the relatives of Lockerbie victims and to prevent Libyan independence day being made into a celebration of Megrahi's return? Yes, and as we saw yesterday, he did not appear at those events."
Scotland's SNP Government was this evening facing almost certain defeat in a vote at Holyrood after coming under sustained attack in a debate on its decision to free Megrahi.
Scottish Labour justice spokesman Richard Baker said the way in which the decision was reached was "chaotic", "badly mishandled" and "reflected badly on Scotland".
But First Minister Alex Salmond insisted Justice Secretary Kenny MacAskill's "difficult, challenging and brave decision" was taken in line with due process and said he was proud to have Nelson Mandela's support for the move.
Former home secretary Jacqui Smith broke ranks to criticise the decision to release Megrahi, saying it did not "feel right".
Ms Smith told BBC Radio 2: "Of course we have to be compassionate with people who are in prison and coming to the end of their lives, but I am not sure I would have made the same decision."Reuse content