US Defence Secretary Leon Panetta was in Tripoli on Saturday on the first visit to Libya by a Pentagon chief to study up close the security needs of the new government.

During the visit, which was to last only a few hours, Panetta was to meet Defence Minister Osama Jouili and Prime Minister Abdel Rahim al-Kib, an AFP correspondent travelling with him said.

"The purpose of my trip to Libya is to have an opportunity to look at that situation up close but to also pay tribute to the Libyan people to what they did in bringing (Moamer) Kadhafi down and trying to establish a government for the future," Panetta told the travelling press.

"There are going to be challenges here, there are going to be difficulties, but I think any country like Libya, that was able to do what they did and showed the courage that they did ... I'm confident that ultimately they're going to be able to succeed in putting a democracy together in Libya.

"The indications I've had are that they're making progress, trying to bring the tribes together, trying to get the country together."

"They have earned the right to try to determine their future, to work their way to the issues that they're going to have to confront.

"Obviously, we're prepared, if they want to, provide whatever assistance they ask us to do. NATO countries have indicated the same willingness to do that."

Enforcement by the Atlantic alliance of a UN-mandated no-fly zone over Libya was crucial in the months-long battle to oust Kadhafi that began in February.

Libya's new rulers are also facing a big challenge as they try to disarm militiamen who fought to topple Kadhafi and secure thousands of surface-to-air missiles stockpiled under the former regime.

Pressure to disarm the former rebels has mounted after local media reported several skirmishes between militia factions in Tripoli, with some resulting in casualties.

There are concerns that the Man-Portable Air Defence Systems, or MANPADS, could be used by militant groups against commercial airliners and helicopters.

Panetta travelled to Libya from Turkey, where he held wide-ranging talks. On Thursday, he was in Iraq to take part in a ceremony marking the end of the US mission.

His visit came a day after the United Nations and the United States lifted sanctions on Libya's central bank in a bid to ease a cash crunch in the post-Kadhafi era, diplomats said.

The Tripoli authorities have stepped up calls in recent weeks to release the estimated $150 billion frozen abroad to help pay salaries and keep services running.