Scottish ministers and officials have declined a request from the United States Senate that they attend a hearing to explain the Scottish government's decision last year to free the convicted Lockerbie bomber on compassionate grounds.
Abdelbaset al-Megrahi, convicted of bombing a US-bound jumbo jet over Lockerbie in 1988, was released from a Scottish prison last August because he was dying.
The foreign relations committee wanted Scotland's justice secretary and prison service's medical chief to testify.
However, the Scottish government said it was accountable to the Scottish parliament and not the US Senate.
The committee has also formally invited Jack Straw, who was justice secretary at the time the Lockerbie bomber was freed.
