The United States is demanding a retraction of a statement by Libya's Prime Minister that the government in Tripoli has not accepted responsibility for the 1988 bombing of a U.S. Pan Am jetliner over Scotland. The statement by the Libyan official, Shokri Ghanem, prompted the Bush administration to call off a planned announcement that it was relaxing restrictions on travel to Libya.

The statement by Mr. Ghanem has brought at least a temporary halt to the rapid warming of U.S.-Libyan relations that followed Libya's decision in December to scrap its nuclear weapons program.

The Libyan Prime Minister said in a BBC radio interview that Libya had decided to "buy peace" by agreeing to pay compensation to the families of victims of the Pan Am 103 bombing, and he responded in the affirmative when his interviewer asked if this meant Libya did not accept guilt for the attack.

State Department spokesman Richard Boucher said Mr. Ghanem's comment directly contradicted the formal Libyan acceptance of responsibility for the attack to the U.N. Security Council last August, which was the basis for the council's decision to lift sanctions against Libya.

He said the prime minister's remarks were "impossible to reconcile" with the August 15 statement and said the United States is demanding a retraction.

"It's the responsibility of the Libyan government to retract statements that contradict what they've officially and authoritatively told the United Nations in writing and on which basis the United Nations Security Council acted," he said. "They said unequivocally in their letter of August 15 of 2003 that Libya accepts responsibility for the actions of its officials. That's a statement that we believe was necessary and remains important. And it will be for the Libyan government to try to explain the comments by its prime minister, or more importantly, to retract them," he said.

The remarks of Mr. Ghanem prompted an outcry from Pan Am 103 families. And a senior U.S. diplomat said it caused the Bush administration to postpone a planned announcement Tuesday lifting the ban on travel to Libya by U.S. citizens that had been in effect since 1981.

The State Department had scheduled a special news briefing on the lifting of the travel ban and related financial sanctions but canceled it at the last minute.

It was to have been the first tangible reward for the Libyan decision in December, capping months of secret talks with the United States and Britain, that it was scrapping a nuclear weapons program and other weapons of mass destruction activities.

The senior diplomat said the prime minister's remarks had been raised at a high level with the Libyan government, which he said promised to make a statement of clarification "very soon."

He said the affair fits a pattern of contradictory statements by Libyan officials on the airliner bombing and said that the United States wanted a clear statement of policy.