New York's US senators are asking the Libyan transitional government to hold the convicted Lockerbie bomber fully accountable for his terrorist actions.
Abdelbaset Ali Mohmed al-Megrahi was convicted and imprisoned in Scotland for the 1988 bombing of Pan Am Flight 103.
The bombing killed 270 people, including 189 Americans.
The Scottish government released Megrahi in 2009, believing he would soon die of cancer.
He was greeted as a hero in his native Libya and met with leader Muammar Gaddafi, whose 42-year rule now teeters on the brink of collapse.
Senators Kirsten Gillibrand and Charles Schumer have called for Megrahi to be returned to prison.
Scottish officials said they want to contact him soon to ensure they will still be able to oversee his parole.