The White House has called for the Libyan man convicted of the 1988 Lockerbie bombing to be returned to prison in Scotland.
Counter-terrorism adviser John Brennan said the release by the Scottish government of Abdelbaset al Megrahi was inappropriate and wrong.
Scottish ministers last year freed Megrahi, who has cancer, citing medical advice that he would likely die in three months.
Mr Brennan says he should complete the remainder of his prison sentence.
The Scottish government says the decision to free him was taken in good faith.
US Secretary of State Hillary Clinton also said in a statement on Friday that the US continued to "categorically disagree" with the decision to release Megrahi, who was sentenced to life in prison in Scotland in 2001 for the bombing.
Following his release in August 2009, he was given a hero's welcome in Tripoli.
Of the 270 people who died in the bombing over Lockerbie, Scotland, 189 were Americans.
