Libya is cooperating fully with a team of visiting US and British officials who are studying how to dismantle and destroy its weapons of mass destruction programs, a senior US official said on Wednesday.

The official raised the possibility that Washington could within months begin easing US economic sanctions on Tripoli if it continues to cooperate on the weapons and addresses US allegations of support for ?terrorism? and meddling in Africa.

In a sign of warming ties, six US members of Congress led by Rep. Curt Weldon, a Pennsylvania Republican, plan to visit Libya this weekend in the first congressional visit since President Muammar Gaddafi seized power in the Arab state 35 years ago.

The US official said a team of about 12 to 15 US and British weapons experts arrived in Libya on Sunday and were getting what they needed from Libyan officials, saying they could soon be ready to remove weapons-related equipment.

?As of now, the Libyans have been very cooperative ... it?s a day-by-day thing,? said the US official who asked not to be named. ?Nobody has any complaints at this point.?

After nine months of secret diplomacy with the United States and Britain, Libya announced a surprise decision on December 19 to abandon efforts to acquire nuclear, chemical or biological weapons in an effort to end its pariah status.

The official said the US-British team was studying issues like how to dismantle and physically remove the bulk of the Libyan nuclear arms program from the country and how to deal with mustard gas stocks, which would be destroyed locally.

He said Libya denied having an offensive biological weapons program but added, ?that is a subject for further discussion.? The group follows initial visits by intelligence teams in October and December that surveyed Libyan arms programs and encountered some resistance that eventually disappeared.

?The first visits ... didn?t proceed completely free of difficulty and things got better as time went on,? said the US official. ?That is why this remains a performance-based question. If we get access to everything we ask for and we get cooperation then we proceed and if we don?t, then we don?t.?

Libya?s August admission of responsibility for the 1988 Lockerbie bombing and its promise to abandon weapons of mass destruction has set the stage for a possible end to US economic sanctions and even the reopening of a US embassy.

Lifting sanctions would allow US oil companies, including the Oasis Group that includes Marathon Oil Co., Amerada Hess and ConocoPhillips to resume work in Libya they abandoned when sanctions forced them out in 1986.

Arshad Mohammed