TRIPOLI — Protesters stormed Libya's national assembly on Tuesday derailing a vote on a cabinet line-up in a new blow to efforts to form a government after a landmark July election.

As he adjourned the session amid chaotic scenes, assembly president Mohammed Megaryef angrily denounced a situation he said was "out of control" more than a year after the overthrow and killing of veteran dictator Moamer Kadhafi.

Prime minister-designate Ali Zeidan, the second nominee to try to form a government since the July vote, had put before the assembly a 30-member list that includes liberals and Islamists.

But as assembly members prepared to take turns to cast their vote, angry scenes erupted on the floor of the chamber and around a dozen demonstrators burst in, live television footage showed.

Demonstrators have managed to force their way into the assembly building on more than one occasion since it was elected, highlighting the vulnerability of the country's transition from dictatorship to democracy.

"What happened constitutes psychological pressure on the members of the congress," Megaryef said.

"Let it be known to all Libyans and to the whole world in what conditions we are working... The situation is out of control," he said.

Megaryef suggested that the assembly reconvene on Wednesday for a new attempt to vote on the line-up put forward by Zeidan.

The premier-designate was elected on October 14 after his predecessor, Mustafa Abu Shagur, was dismissed in a vote of no confidence as the assembly rejected his proposed line-up as unrepresentative of Libya's numerous factions.

Zeidan's programme puts heavy emphasis on reforming the army and police, which remain heavily dependent on the myriad of former rebel militias that have yet to be brought under unified command since last year's uprising.

"I decided to put independents in charge of the ministries of foreign affairs, international cooperation, finance, justice, interior and defence," Zeidan told the assembly.

Among Zeidan's nominations are Mohammed al-Barghathi as defence minister and Ashur Shwayel as interior minister. Both are natives of second city Benghazi, cradle of last year's uprising.

Barghathi, a 71-year-old fighter pilot who retired in 1994, was one of the first former officers to join the rebellion.

Shwayel, 58, has a doctorate in law and served 35 years in the police force.

Zeidan nominated Ali Aujli, Libya's ambassador to the United States, as foreign minister and Abdelbari al-Arussi, a native of the western town of Zawiyah, to head the strategic oil ministry.

He also proposed creating a new ministry of tourism, a first for the ultra-conservative Muslim country. It would be headed by Ikram Bash Imam, one of two women in the line-up.

The chief task of the next government is organising fresh elections within 12 months on the basis of a new constitution, which has yet to be drafted.

The assembly must approve the government team before Zeidan, a long-time Kadhafi opponent, can assume office and replace Abdel Rahim al-Kib, who has held the post since November.

The suitability of several nominees, including the ministers of foreign affairs and religious affairs, was called into question by several assembly members, assembly sources said.

The 200-member assembly has the option of rejecting the government team as a whole or requesting that it be amended if there are reservations over one or more of the ministers.

Zeidan, who won his post thanks in large part to the backing of the liberal National Forces Alliance, the largest party in the congress, said on Tuesday he had reached out to all the main political factions when forming his government.

A 62-year-old career diplomat, Zeidan defected in 1980 while he was serving at the Libyan embassy in India, and spent the next three decades in exile.

He played a major role in winning international recognition for the rebel leadership during last year's uprising which saw the rebels vanquish Kadhafi's forces with the UN-endorsed support of NATO.