Barack Obama is under pressure to release a letter sent to Scottish ministers by a senior diplomat at the US embassy in London last August, which the Scottish government say "grudgingly supported" freeing the Lockerbie bomber on compassionate grounds.
The Scottish government feel that this letter undermines Obama's public position, where he has claimed to be "surprised, disappointed and angry" by the Libyan's release.
The Scottish government have been pressured by the US Senate's foreign relations committee to allow the Scottish justice minister, Kenny MacAskill, to appear in front of their Lockerbie hearing to explain his decision. Alex Salmond, the Scottish First Minister has refused to allow this.
So, the US position appears to have been not against the release of Megrahi, but against his return to Libya. The Americans made clear that keeping Megrahi in Scotland "would mitigate" many of their concerns.
The existence and content of the US embassy note was first disclosed by the Guardian last August, at the height of the controversy over Megrahi's release, and its full text has now been leaked to the Sunday Times.
In it, the deputy head of the US embassy in London, Frank LeBaron, said the US believed Megrahi should remain in Greenock jail because of the seriousness of his conviction for killing 270 passengers and crew, and 11 Lockerbie townspeople, by bombing Pan Am flight 103 in 1988.
But he added: "Nevertheless, if Scottish authorities [conclude] that Megrahi must be released from Scottish custody, the US position is that conditional release on compassionate grounds would be a far preferable alternative to prisoner transfer, which we strongly oppose."
LeBaron said releasing Megrahi but making him live in Scotland "would mitigate a number of strong concerns we have expressed with regards to Megrahi's release."
Allowing Megrahi to live outside prison in Scotland was one of the options considered by MacAskill. Megrahi's wife and sons had a family home paid for by the Libyan government in the prosperous Glasgow suburb of Newton Mearns. But that option was rejected after police advice that this would cause immense security and logistical problems, and cost £100,000 a week to protect him. The house would need a 24-hour armed guard, while Megrahi would need heavy security for his regular trips for medical treatment.This option was apparently considered, but rejected on the grounds of costs.
Click here for full article.