UK ministers have released documents detailing their correspondence with the Scottish Government over the fate of the Lockerbie bomber.
Jack Straw changed his mind about excluding the Lockerbie bomber from a proposed prisoner transfer agreement with Libya, letters have shown.
The Scottish Government is also set to publish documents it says will justify the decision to release the Libyan on compassionate grounds.
The UK's justice secretary initially agreed anyone connected with the bombing should be excluded.
Eight letters between the governments, dating back to 2007, were published on the UK Ministry of Justice's website.
But in a later letter to the Scottish Government he said it was in the UK's interests the agreement should take a "standard form".
Terminally ill Abdelbaset Ali al-Megrahi was freed on 20 August.
Terminally ill Abdelbaset Ali al-Megrahi was freed on 20 August.
The Scottish Government announced the publication amid strong criticism of the decision to release Megrahi.
He was released by Scottish Justice Secretary Kenny MacAskill on compassionate grounds, after the minister rejected a prisoner transfer request.
Westminster sources have indicated the UK government correspondence is said to support its position that no deals were done with Libya to secure Megrahi's freedom.
The UK government has released its letters to Scottish ministers over the issue.
UK Justice Secretary Jack Straw has previously described reports that the bomber was released over an oil deal as "wholly untrue".
The Scottish Government is also publishing background reports on the case which it has said will justify its final decision.
BBC political correspondent Iain Watson says the Westminster government is keen to emphasise there was no secret deal with Libya, following negative newspaper stories at the weekend.
The Ministry of Justice was first to publish several letters from the then Justice Secretary Lord Falconer to Scottish First Minister Alex Salmond, along with letters from his successor Jack Straw to Mr MacAskill and Mr Salmond.
"And they are equally anxious to prove that they did not place pressure on the Scottish government to allow the only man to be convicted of the Lockerbie bombing to return home on compassionate grounds.
In a letter to Mr MacAskill in September 2007, Mr Straw agreed with the Scottish Government's proposal that anyone convicted of the Lockerbie bombing would be excluded from a prisoner transfer agreement between the UK and Libya.
"They believe that by making all relevant documents public today, they will strengthen that case."
But in a follow-up letter, dated 19 December, Mr Straw said he would not be able to secure such an exclusion, writing: "Wider negotiations with the Libyans are reaching a critical stage and, in view of the overwhelming interests for the United Kingdom, I have agreed that, in this instance, the PTA should be in the standard form and not mention any individual."
Mr MacAskill said the Scottish Government was seeking to act "openly and accountably" and had "nothing to hide".
In a further letter to Mr Salmond, on 11 February 2008, Mr Straw said Libya had become an "important partner in the fight against terrorism".
'Due process'
Hero's welcome
"There's some information that people don't want to be released and we're not going to force that," he said.
He added: "Libya is in a key position to help stem the flow of illegal migrants to the EU and to the UK."
"But we've got nothing to hide and therefore we are delivering on what we said - which is that we would act according to due process, following the rules and guidance in Scotland, and we would publish what we were entitled to."
Mr Straw has previously said reports that the Lockerbie bomber was released over an oil deal are "wholly untrue".
In an interview with the Financial Times, Prime Minister Gordon Brown said that, when he met Libyan leader Colonel Gaddafi at the G8 summit a month before Megrahi's release, he had stressed the fate of Megrahi was a matter solely for the Scottish authorities.
Mr Brown said: "I made it absolutely clear to him... it was a matter for the Scottish Executive and it was their decision, and their decision alone, that would decide it."
The question is, is it all the documents involved? Ed DaveyLib Dem foreign affairs spokesman Send us your comments
Meanwhile, David Cameron has renewed pressure on Mr Brown to say whether he agrees that Megrahi should have been released.
The Conservative leader said the decision to free the Lockerbie bomber on compassionate grounds was "inappropriate".
He told the Times: "Decisions concerning the fate of criminals, not least those responsible for mass murder, often provoke widespread public anger.
"But the outrage at this one has crossed continents and damaged our relationship with our closest ally, America. It has been a fiasco."
The Liberal Democrat foreign affairs spokesman, Ed Davey, welcomed the chance to see the correspondence.
But he added: "The question is, is it all the documents involved?
"Will we still have to have some sort of Foreign Affairs Select Committee inquiry, so ministers can actually be questioned, so we can get some of the background to the letters and to any conversations that were held?"
The publication of documents in Scotland came ahead of a government-led Holyrood debate on the case on Wednesday.
The government motion for Wednesday's debate notes the decision to grant Megrahi compassionate release and reject a prisoner transfer to Libya was consistent with the principles of the Scottish justice system.
Opposition parties will attempt to amend the motion and inflict a defeat on Scottish ministers over the issue.
Megrahi was freed after serving eight years of a life sentence for the bombing, which led to Pan Am flight 103 exploding over the town of Lockerbie in December 1988.
Megrahi was freed after serving eight years of a life sentence for the bombing, which led to Pan Am flight 103 exploding over the town of Lockerbie in December 1988.
The decision to release Megrahi, who was given a hero's welcome when he arrived back in Libya, has divided opinion at home and abroad.
The decision to release Megrahi, who was given a hero's welcome when he arrived back in Libya, has divided opinion at home and abroad.
The controversy has prompted many Western leaders to stay away from celebrations in Libya this week to mark 40 years since the coup that brought Colonel Gaddafi to power.
The controversy has prompted many Western leaders to stay away from celebrations in Libya this week to mark 40 years since the coup that brought Colonel Gaddafi to power.
