Libyan Foreign Minister Omar al-Muntasser responded over the weekend to a letter of assurances from U.N. Secretary-General Kofi Annan about the trial and requested clarification of "some elements," said U.N. spokesman Fred Eckhard.

He refused to elaborate, but U.N. officials and diplomats said al-Muntasser raised two issues: the lifting of sanctions against Libya and the imprisonment of the two Libyans in Scotland if convicted.

These are the same issues that Libya objected to when the United States and Britain made a joint proposal in August for a trial in the Netherlands under Scottish law. The bombing over Lockerbie, Scotland, in December 1988 killed 270 people.

The U.N. Security Council made clear that if the two Libyans were not handed over promptly, it would consider further sanctions -- and on the 10th anniversary of the crash on December 21, the United States and Britain set a deadline to coincide with a scheduled February review of sanctions against Libya.

There now appears to be little chance that the Libyan government will turn over the men for trial before the Security Council reviews sanctions on Libya on Friday.

Deputy U.S. Ambassador Peter Burleigh said in December that the United States would press for additional measures "to compel compliance." U.S. diplomats have suggested that Washington might press for new oil-related sanctions.

Libya wants sanctions lifted for good

A Security Council resolution in August, backing the Anglo-American initiative, pledged to suspend sanctions as soon as the two Libyans arrived for trial. The sanctions include a ban on air travel, the freezing of some Libyan assets overseas, restrictions on diplomatic personnel, and a ban on the purchase of oil equipment.

Libya wants sanctions lifted -- not just suspended -- when the men are turned over.

But under a 1992 resolution that imposed sanctions, the Security Council said the measures will remain until Libya cooperates fully in establishing responsibility for the bombing and until the Libyan government commits itself "definitively to cease all forms of terrorist action and all assistance to terrorist groups."

Libya must also "demonstrate its renunciation of terrorism," the resolution said.

The letter Annan sent to Libyan leader Moammar Gadhafi last Wednesday has not been made public. Diplomats at the United Nations said that Annan proposed that Scottish prosecutors should not attempt to undermine the Libyan government, but added that the trial would still need to delve into the motives behind the bombing.

Al-Muntasser's reply also was not released.

Eckhard said the secretary-general was studying the letter and would report to the Security Council