Labour and Conservative spokesmen today demanded answers from Alex Salmond over why his government asked Donald Trump to back the decision to release Abdelbaset al-Megrahi, the man convicted of the Lockerbie bombing.

A leaked email from Geoff Aberdein, one of the First Minister’s special advisers who is now his Chief of Staff, shows him drafting a statement for Mr Trump in 2009, when the two men were on good terms following the Scottish Government's decision to approve the planning application for his golf resort in north-east Scotland.

The prepared statement read: "It (releasing Megrahi) must have been a hugely difficult decision for the Scottish Government to make and, of course, for most of our own United States families who lost loved ones, it would always be impossible to accept.

"Their reaction is entirely understandable and, as an American, I personally would sympathise with the US families. However I am certain that the Scots issued this release for good reasons and I would hope that it might break the cycle of violence around the world, and replace it with reciprocal gestures.

"In any event it won't stop my love affair with Scotland and the Scots. No one should ever demean that country."

But Mr Trump declined to issue the statement, and his relationship with Mr Salmond later broke down after it emerged that an offshore windfarm was planned near to the site of his links course.

The Trump Organisation claimed the approach three years ago was an attempt by the First Minister to get something in return for stepping into the row over the US businessman's controversial golf course application in Aberdeenshire.

"We received a number of phone calls, initially from Geoff Aberdein, talking about the possibility of Mr Trump or the Trump Organisation issuing a statement supporting Scotland's decision to free the Lockerbie bomber," a Trump Organisation spokesman said.

"The mere suggestion that Mr Trump would do that was offensive and absurd. As Americans and New Yorkers who have unfortunately suffered and seen terrorism first-hand, it was ludicrous. The answer was no."

The spokesman said the First Minister was under political attack for the decision, announced by Justice Secretary Kenny MacAskill in 2009.

"He was very unhappy and demanded to speak to Mr Trump," he said.  "He was demanding and insisted he had helped us and now it was time to help him."

The accusation comes while Mr Trump is locked in an increasingly bitter planning battle to stop a wind turbine test centre being built in the North Sea in view of his golf course to the north of Aberdeen.

In a series of highly-critical comments, Mr Trump has turned from speaking warmly of Mr Salmond to calling him mad.

Today, the Trump Organisation spokesman likened the First Minister to Iranian president Mahmoud Ahmadinejad. "He ignores due process and rams his own agenda through the system," the spokesman added, concerned that the proposed European Offshore Wind Deployment Centre is destined to go ahead.

Lewis Macdonald, Labour’s justice spokesman, called on the First Minister to explain why he asked Mr Trump to endorse the early release, warning that the integrity of Scottish politics is at stake.

He said: “Alex Salmond needs to tell the Scottish people why he thought it was appropriate to use his political and personal relationship with Donald Trump to gain support for such a controversial decision.

“As well as raising questions about the way that the First Minister runs his office, these revelations suggest that Mr Salmond expected Mr Trump would be willing to sign up to his pre-drafted statement. It would appear that the First Minister thought Mr Trump had a favour to return, even if the US tycoon didn’t agree.

"It is extremely worrying that such close relationships between politicians and rich and powerful businessmen can affect Scottish Government policy. Mr Salmond needs to come clean not only about this particular email, but about what other emails were sent in similar circumstances and whether any of his pleas for support proved to be more successful.”

Scottish Conservative deputy leader Jackson Carlaw said: "Alex Salmond needs to explain without delay what on earth the Scottish Government was thinking when it took this action.

"Donald Trump, like most people in Scotland and almost everyone in the US, clearly realised the release of Megrahi was a huge mistake. This is another murky development in a sorry saga.

"This attempt by one of Alex Salmond's 13 special advisers to curry favour from, of all people, Donald Trump for such a controversial decision is as bizarre an example of attempted SNP spin as it is inappropriate and offensive to the memory of those who lost their lives and to their families. At the very least both an explanation and a public apology are required from Alex Salmond.”

A spokeswoman for the First Minister said: "The Scottish Government took an important decision to release Abdelbaset al-Megrahi on compassionate grounds, a decision made in good faith.

"We were perfectly entitled to hope for support from international stakeholders. Indeed Nelson Mandela, Desmond Tutu, among many others around the world, supported this decision. We understand Mr Trump did not support this decision which was entirely up to him.

"None of this will have any bearing on the Scottish Government's proper consideration regarding the European Offshore Wind Deployment Centre."