Tom Lantos arrived in Tripoli on Saturday to begin the first visit by a member of the US Congress to Libya since Muammar Gaddafi took power in the oil-rich North African country 34 years ago.
Representative Lantos of California, the House International Relations Committee's top Democrat, will be followed by six other lawmakers on Sunday for talks with senior Libyan government officials, parliament members, businessmen and others, Libyan officials said.
"The US Congress and the US administration are looking forward to working intensively and conclusively with the government here," Lantos told reporters at Tripoli's airport.
Libya is widely believed to want a speedy normalisation of its diplomatic relations with the United States, which banned Libyan oil imports in 1982 and in 1986 expanded sanctions, accusing Tripoli of sponsoring terrorism.
Senior US officials have hailed Gaddafi's pledge last month to renounce efforts to acquire nuclear, chemical and biological weapons. Officials from the United States, Britain and the International Atomic Energy Agency were in Libya this week to begin dismantling its nuclear facilities.
US officials have sent mixed signals about when and how they might ease sanctions and restore diplomatic links.