Eager voters cast ballots on Saturday in Libya's first free national elections for decades after the ouster of dictator Moamer Gathafi, but protesters disrupted some polling in the troubled east.

In Tripoli, voting got underway with queues of people keen to elect the General National Congress, which will be at the helm of the country for a transition period.

"Words cannot capture my joy, this is a historic day," said Fawziya Omran, 40, one of the first women in line at the Ali Abdullah Warith school in the heart of the capital.

"I've made my choice. I hope it is the right choice and that the candidate will not disappoint us," she said.

Voters in the capital turned up draped in black, red and green flags -- the colours of the revolution that toppled Gathafi last year -- while mosques blasted chants of "Allahu Akbar" (God is greatest).

Joy was also palpable in the eastern city of Benghazi, cradle of the uprising.

"I feel like my life has been wasted so far, but now my children will have a better life," said Hueida Abdul Sheikh, a 47-year-old mother of three in line.

However, protesters calling for greater representation forced the closure of several polling stations elsewhere in the tense region.

Some voting centres were shut in the eastern city of Ajdabiya, where a depot containing electoral material was torched this week, an official said.

Another said voting was disrupted at southeastern oasis, including Jalo and Ojla, after federalism supporters prevented a plane carrying polling material from taking off.

And Abdeljawad al-Badin, spokesman of the self-appointed Cyrenaica Council, said voters in Quba, near the town of Derna, were boycotting the election altogether.

Protesters in the east, unhappy over the distribution of seats in the new assembly, had threatened to sabotage the vote, staging a string of disruptive acts of violence in recent days.

In Tripoli, a senior electoral official confirmed there had been some incidents in the east but dismissed reports the vote could be delayed in those areas, stressing they were working towards a solution.

"Ninety-two percent of voting centres are open," he said.

Interim leader Mustafa Abdel Jalil, who voted in his eastern home town of Al-Bayda, said the situation there was "excellent." He expressed hope for a successful vote and hailed as a martyr an electoral worker killed on Friday.

"We hope that our brothers in Benghazi will stay away from such problems and that the voting will go ahead as planned," he said.

Alexander Graf Lambsdorff, who heads a team of 21 European Union observers, said the vote marks a major milestone in the transition to democracy after 42-years of dictatorship.

"We believe that to have this election in Libya less than one year after the fall of Tripoli is an important achievement," Lambsdorff said.

"We only hope that the situation remains peaceful across the country. The majority of Libyans want to vote. Eighty percent want to vote."

On the eve of the ballot, gunfire struck a helicopter in eastern Libya killing an election worker.

Also, five oil facilities were forced to shut down by gunmen who want greater representation for the east in the 200-member congress.

And on Sunday, gunmen ransacked the office of the electoral commission in Benghazi.

The make-up of the congress has been a matter of heated debate, with factions such as the federalist movement calling for more seats.

The outgoing National Transitional Council (NTC) says seats were distributed according to demographics, with 100 going to the west, 60 to the east and 40 to the south.

But factions in the east want an equal split and had threatened to sabotage the vote if this demand is not met.

The authorities dismiss such groups as a minority, pointing out that more than 2.7 million people, or about 80 percent of the electorate, have registered to take part in the poll.

Libya has not seen elections since the era of the late King Idris, whom Gathafi deposed in a bloodless coup in 1969.

Parties were banned as an act of treason during Gathafi's iron-fisted rule. Now there are 142 parties fielding candidates.

A total of 80 seats are reserved for party candidates while 120 seats are open to individual candidates. Altogether, 3,707 candidates are running in 72 districts across the country.

From the parties, the coalition of ex-war time prime minister Mahmud Jibril is seen as a key contender among liberals, facing stiff competition from two Islamist parties -- Justice and Development and Al-Wattan.

The winds of the Arab Spring that ushered Islamists into power in neighbouring Tunisia and Egypt may well bring the same result.

The incoming congress will have legislative powers and appoint an interim government. But it no longer has the right to appoint a constituent authority, under a last-minute amendment issued by the NTC, and the body will be chosen in a separate election.

A February 2011 uprising ended more than four decades of the dictator who was killed while on the run in October.