The United States is publicly calling on France not to "impede" an agreement under which Libya is to pay compensation for the downing of Pan Am flight 103 over Lockerbie, Scotland in 1988. France is threatening to veto an enabling resolution in the U.N. Security Council to press for a similar settlement for family members of a French plane brought down over Niger.

Bush administration officials are making little effort to conceal their irritation over the French stand, which threatens to scuttle the painstakingly negotiated agreement on compensation for the Pan Am 103 attack.

Under the deal announced last week, Libya accepted responsibility for the Pan Am bombing and agreed to pay as much as $2.7 billion in compensation to the families of the 270 victims, provided that among other things the U.N. Security Council permanently lifted U.N. sanctions against the Muammar Gadhafi government.

On Monday, Britain and Bulgaria introduced a resolution to lift the sanctions which U.S. officials hope can be approved by the end of the week.

But France is threatening a veto unless French lawyers are given time to broker a similar deal for the French UTA jetliner allegedly downed by a Libyan bomb over Niger in 1989.

France accepted a $33 million settlement for the families of the 170 UTA victims four years ago, and at a briefing here State Department spokesman Richard Boucher noted that France told the Security Council in 1999 that Libya had met council requirements in the UTA case.

He said that the United States, while supporting compensation for all terrorist victims, is "deeply concerned" about possible actions by France or any other country that would impede the Pan Am 103 settlement.

"We continue to support compensation for all victims of terrorism, including the UTA families," said Mr. Boucher. "At the same time we don't believe such efforts should impede the council's consideration of Libyan sanctions, once requirements in the resolutions have been addressed. Nor should the Pan Am 103 families, who have waited so long for some measure of justice and closure, have their settlement threatened by extraneous last-minute factors."

Mr. Boucher said the vacationing Secretary of State Colin Powell discussed the Libyan issue by telephone with British Foreign Secretary Jack Straw Tuesday, and that there were ongoing U.S. contacts with France "at a very senior level."

A senior U.S. diplomat indicated those contacts were blunt, and that more direct criticism of the French position can be expected if France does veto the U.N. resolution.

U.S.-French relations have only recently begun to recover from the strains of earlier this year, when France blocked Security Council authorization of the American-led military action that ousted Saddam Hussein in Iraq.