Labour justice spokesman Richard Baker has revealed that he is to meet an official connected to the US Senate inquiry into the release of the Lockerbie bomber.
Mr Baker said he will call for publication of the bomber's medical reports when he meets the representative of US Senator Robert Menendez in Edinburgh on Thursday.
The MSP said: "Kenny MacAskill and other SNP ministers took the decision to release (Abdelbaset Ali Mohmed al) Megrahi and the medical evidence that they relied upon has not been published.
"I will make it clear that to get to the truth of the matter the Senators should focus their attentions on that advice."
Senator Menendez is a member of the Committee on Foreign Relations which has launched an inquiry into the release of Megrahi.
The Libyan is the only person convicted of the 1988 bombing of Pan Am Flight 103 over Scotland, in which 270 people died - most of them Americans.
Scottish Justice Secretary Kenny MacAskill released him on compassionate grounds after he was given three months to live but he remains alive today.
His release 13 months ago sparked fury in America and has been condemned by Barack Obama's administration.
A Labour spokeswoman said Mr Baker will make it clear only publication of full medical reports "will reveal new information on the flawed release of the Lockerbie bomber".
She said the MSP will advise the Senate "emissary" that its investigation should focus on the medical advice given to ministers and the opinions of the doctors who gave advice on Megrahi's life expectancy.