Dr Jim Swire has written to former US Presidential hopeful Senator John Kerry to request that the US convene a wide ranging inquiry into the circumstances of the Lockerbie airliner incident in December 1988.

"I do not feel proud of the circumstances that have led me to hope that representatives of the USA rather than my own nation should be searching for the truth on our behalf," Swire says.

"The failure of any UK Prime Minister to date to inquire into this ghastly failure of UK responsibility is enough in itself to justify this letter appealing to you. We have approached every Prime Minster to seek a full inquiry and been as often rejected."

Senator Kerry is leading a group of four US senators who are scheduled to convene an inquiry on 29 July looking into the circcumstances surrounding the release of Abdelbaset Ali Mohmed Al Megrahi, and whether oil company BP had any role in those events.

Swire's letter highlights the role of former Justice Secretary Jack Straw, stating that Straw was "reduced to overriding the wishes of the House of Commons Select Committee on Human Rights, in order to have the Prisoner Transfer Agreement up and running by the start of the appeal."

The letter also criticises former Prime Minister Tony Balir's meeting with Libya's Colonel Gadaffi, at which it is alleged oil trading arrangements were discussed.

"He did meet with us but after a month of ‘asking the relevant people’ told us that ‘they’ did not consider any further inquiry necessary. When he went to see Colonel Gaddafi for the so called ‘Deal in the Desert’, the first we heard of it was through the media," Swire says.

"In the event the Scots did not use the Prisoner Transfer Agreement, but compassionate release, an option long enshrined in Scots law, when a prisoner has a short life prognosis (there is no ‘deadline’ of three months by the way) but for some reason Mr Megrahi withdrew his appeal, though this was not required for Compassionate release. Was pressure put upon him to do so? Maybe a proper inquiry would answer that question too.

"You may of course believe that it was pressure from BP which caused the panic, if Libya or BP were claiming that the UK was dragging her feet over her share of the ‘Deal in the Desert’. Maybe you can find out whether it was that or a desire to 'protect' the verdict which motivated Mr Straw's precipitate actions.

"Senator Kerry, I am heartened to hear that UK Prime Minister David Cameron has just undertaken to meet with you after all, according to today’s press. But I do wonder in view of the behaviour of successive UK governments, with all their delays and withholding of information over the past 21 years, and their failure to protect the plane in the first place, whether the Government of the UK is the right entity to hold an inquiry into this atrocity.

"Would it be putting the fox in charge of the hencoop?"

Professor Robert Black has also criticised the limited release of documents sanctioned by David Cameron.

"For a fleeting instant I naively entertained the thought that the documents might be those in respect of which the UK government, acting through then Foreign Secretary David Miliband, in Mr Megrahi's most recent appeal claimed public interest immunity on grounds of national security," Black said.

"The circumstances in which Mr Megrahi was returned to his homeland are to be the focus of the document review rather than the circumstances in which he was wrongly convicted. Any meaningful inquiry would, of course, be too embarrassing to both the UK and the USA to be contemplated."

Last week MSP Christine Grahame challenged the US Government to convene a "thorough and comprehensive" review of the Lockerbie affair, claiming there were "large state interests, both in the US and UK, eager to see that the truth behind Lockerbie never emerges."

Dr Swire's letter can be read in full, here.