"We're very excited and pleased about the direction your leader has taken. We want to be friends," the head of the delegation, Pennsylvania Republican Curt Weldon, told the Libyan officials who met the delegation at Tripoli airport.
The lawmakers arrived on a US Navy plane and Weldon said it was the first US military aircraft to land in Tripoli since al-Qadhafi overthrew the Libyan monarchy in 1969.
Weldon praised al-Qadhafi for his pledge to abandon efforts to possess weapons of mass destruction and for his moves to resolve the 1988 Lockerbie bombing with the United States and the United Kingdom.
"We want to tell him (al-Qadhafi) that because of his actions we are here to start a new time with the Libyans. We are here to take a message back to the American people that our visit has been very positive," he said.
"We achieved results more than we expected in terms of the feelings of a new direction (in Libya). It exceeds our expectations," Weldon added.
"We achieved results more than we expected in terms of the feelings of a new direction (in Libya). It exceeds our expectations"
Head of US delegation to Libya
Another US lawmaker, California Democrat Tom Lantos, arrived in Tripoli on Saturday on a separate mission.
The Libyan government announced last month it was abandoning programmes to develop weapons of mass destruction, opening the way for better relations with the West.
Libya has also taken steps to resolve long-standing disputes over the bombing of a US airliner over Lockerbie, Scotland, in 1988 and a French plane over Niger in 1989.
Libyan Prime Minister Shukri Ghanim said the visiting US lawmakers pledged to lobby hard in Washington to push the US administration to lift its sanctions and allow a swift return for US oil firms to resume work in the country.
"They affirmed that they will work forcibly to end the American embargo against Libya and permit the return of oil US companies as soon as possible to invest in Libya," Ghanim told reporters.
He said the lawmakers were hoping the countries would resume diplomatic links and reopen embassies in Washington and Tripoli "within this year".
"They (US lawmakers)affirmed that they will work forcibly to end the American embargo against Libya and permit the return of oil US companies as soon as possible"
Libyan prime minister
Weldon said his message to the Libyans was that if they took further unspecified steps, then friendship could follow.
"We are here to say that this continued process will allow us to eventually have normal relations and to bring with it improvements in the quality of life for the people of this nation," he told reporters.
"We want to continue that momentum and we are confident that if that happens, then some time in the future, the sanctions will be lifted," he added.
The United States banned imports of Libyan oil in 1982 and had prevented US oil companies from operating the Libyan concessions which they had acquired before the ban.
Meanwhile, Lantos held talks with Trade and Economy Minister Abd al-Qadir Belkhair and during his three-day visit is also expected to meet Foreign Minister Abd al-Rahman Shalgham, as well as business leaders, academics and members of the American expatriate community.