Nearly 100 Libyan gunmen backed by heavy weapons kept the national assembly under siege Thursday in protest at the new premier's cabinet lineup and alleged links of some ministers to Moamer Gathafi's regime.

The protest which erupted on Wednesday night has drawn dozens of former rebels from Tripoli and other cities, some of them formally affiliated with the defence and interior ministries.

"What is happening and the scale of what is going on is very grave," said Othman Ben Sassi, an official linked to the national assembly, which was not in session on Thursday.

He said ex-rebels were occupying the assembly and other official buildings.

Traffic leading to the assembly and the adjacent Rixos hotel was blocked by a dozen 4x4 vehicles and pickup trucks mounted with anti-aircraft guns among other heavy weapons, said an AFP journalist at the scene.

"We are demonstrating against the national assembly and its chosen government because it is made up of remnants of Moamer Gathafi's regime," said Abdel Jalil Maziq, 42, a native of the western city of Misrata.

"The world helped us overthrow the tyrant and now here we are stuck with remnants of his regime," he added.

The complaints centred on members of the new prime minister's cabinet, which was approved by the assembly on Wednesday in a session that was cut short by the protests and mounting security concerns.

The main ministers to have sparked controversy are those of health, foreign affairs, international cooperation, higher education and religious affairs.

"These five are the most problematic," said rights activist Abdelmenam al-Hor, stressing they had played a role in upholding the former regime and should be removed.

Others said nine ministries were in dispute, including the strategic portfolio of oil.

Activists Bashir Rajab said he had come armed with a formal letter of complaint because "people who were with Kadhafi and participated in promoting his green book (manifesto) need to be isolated from the political process."

Tempers flew high with some fighters threatening and shoving the press.

An old woman pleaded: "Please calm down, we want the country to move on."

Many of the gunmen redirecting traffic away from the assembly also complained there were no former rebels in the new government and that their salaries had not been paid.

"It's been seven months since I was paid. These people are stealing our money," charged the commander of a brigade from Misrata who declined to be named.

Gunmen were also present at the luxury Rixos hotel, streaming in casually and passing their pistols through the metal detectors. Some of them, dressed in suits, said they had come to negotiate and submit their demands.

"There are about 20 revolutionaries meeting with the prime minister to discuss their objections," said Colonel Jumaa al-Meshri of a Tripoli-based brigade.

The spokesman of the assembly could not be reached for comment but a security official said there had been "no orders" from the authorities to intervene until now.

Libya's national assembly gave its approval on Wednesday to a 30-member cabinet presented by prime minister-designate Ali Zeidan, weeks after rejecting his predecessor's line-up.

The prime minister and his cabinet still have to be sworn in.

Protesters who barged into the assembly on Tuesday derailed a first session on the cabinet, which was hastily approved in a Wednesday vote-of-confidence as demonstrations erupted outside the building.

The demonstrations coupled with the lack of discipline of former rebels nominally under the state's control underline the fragility of Libya's transition to democracy a year after Gathafi was overthrown.