Libya agreed for the first time yesterday to take a measure of responsibility for the 1988 terrorist bombing that destroyed Pan Am Flight 103 over Lockerbie, Scotland, said a senior State Department official who reported that the offer is being studied carefully.

At a meeting in London with U.S. and British diplomats who have long been negotiating a statement of responsibility, Libyan leader Moammar Gaddafi's emissaries proposed words to accompany a previous offer to pay as much as $2.7 billion to the relatives of 270 victims.

"There is some agreement along those lines with Libya. I'm not in a position to say that it's sufficient," the official said. "We intend to go through it very carefully back here."

Relatives of the passengers who died on Pan Am 103 remained skeptical. They have long pressed Gaddafi to take responsibility for the holiday season bombing, and they have been disappointed before.

Bob Monetti, whose son, Richard, died aboard the jetliner, described himself as "cautious and hopeful, but not optimistic."

"One possibility is that Libya is actually ready to admit responsibility," he said from his home in New Jersey. "A second possibility is that Libya is sorta gonna maybe kind of admit responsibility in some kind of half-baked, deniable way, which is the worst of all possible worlds."

Libya's statement would cover the government's civil responsibility as the employer of individuals connected to the attacks, but not criminal liability, the U.S. official said. The text would need to be approved by the United Nations if international sanctions against Gaddafi's government are to be lifted.

Representatives of the families are due to meet this afternoon in Washington with Assistant Secretary of State William J. Burns, who held talks with the Libyan envoys in London yesterday. U.S. officials said they did not expect Burns to be able to give the families a definitive assessment of the Libyan proposal.

The State Department has said it would look to the families for a signal about the sufficiency of any Libyan statement. Some relatives believe an admission of government responsibility, paired with a large financial settlement, would be adequate. Others have said they will not perceive justice until Gaddafi issues a personal mea culpa.

If the statement is accepted, it would signal a significant step out of isolation for Gaddafi, who has ruled Libya since 1970. Gaddafi wants, for a start, to see the permanent elimination of U.N. economic sanctions, now suspended.

More ambitiously, Gaddafi wants his country to be the first to be removed from the State Department's list of terror-sponsoring states. To succeed, he must convince U.S. authorities that he has forsworn terrorism. U.S. officials signaled their wariness last year by alleging that Libya is trying to establish nuclear and chemical weapons programs.

Under pressure from investigators years after the attack, Gaddafi surrendered two Libyan agents suspected in the Pan Am bombing, which killed 259 people aboard the plane and 11 on the ground. A Scottish court convicted one of the agents, Abdel Basset Ali Megrahi, in February 2001.

A few months later, negotiations with lawyers for the families picked up steam. The attorneys reached a tentative agreement last year that would deliver $10 million to the relatives of each victim in phases tied to Libya's success in eliminating sanctions.

Not only are many families anxious to put the legal fight behind them, but Gaddafi and a number of U.S. oil companies also are keen to do business, which has been prohibited since President Ronald Reagan imposed sanctions before the Lockerbie bombing. Influential members of Congress made clear as recently as last year that U.S. sanctions would not be lifted unless Libya demonstrated a new attitude.

Libyan leader Moammar Gaddafi wants his country to be the first that is taken off the U.S. list of states sponsoring terrorism.