Calls for a boycott and other unrest on the eve of Libya's first vote since the overthrow of longtime dictator Moammar Gadhafi raised fears of election violence, even as campaigning came to an end Friday for a contest seen as a milestone on the country's rocky path toward democracy.

The Saturday election of a 200-member transitional parliament caps a messy nine-month transition after a ruinous 2011 civil war that ended in October with the death of Gadhafi, whose four-decade rule left the country deeply divided along regional, tribal and ideological lines.

The parliament will elect a new transitional government to replace the one appointed by the National Transitional Council that led the rebel side during the eight-month war and held power in its aftermath.

Many in Libya's oil-rich east feel slighted by the NTC-issued election laws, purportedly based on population, that allocate their region less than a third of the parliamentary seats, with the rest going to the western region that includes Tripoli and the sparsely-settled desert south.

In what it called an attempt to defuse east-west tensions, the NTC decreed on Thursday that the new parliament will not be responsible for naming the panel that will draft a new constitution. Instead, the drafters will be directly elected by the public in a separate vote at a later date.

But this has not satisfied some in the east, who press for a boycott.

"We don't want Tripoli to rule all of Libya," said Fadlallah Haroun, a former rebel commander in the east's regional capital Benghazi.

Late Thursday, former rebel fighters from the east shut down three eastern oil refineries - in Ras Lanouf, Brega and Sidr - to press the transitional government to cancel the vote, Haroun said. He added that militiamen also have cut the country's main coastal highway linking east to west.

Earlier this week, ex-rebel fighters and other angry protesters in Benghazi and in the nearby town of Ajdabiya attacked elections offices, setting fire to ballot papers and other voting materials.

Haroun said boycott supporters would take to the streets on election day to "prevent people from voting, because this is a vote that serves those who stole the revolution from us." He said they would not take up arms but when asked how they would stop voters, he said, "We will see tomorrow."

Many in the west are equally dissatisfied with the decree, saying it will undercut the authority of the new parliament.

"The National Transitional Council acts like a rooster with its head cut off," said Yassar al-Bashti, a candidate with the liberal Free Libyans Party. "They want to weaken the new parliament after their failures over the past months."

The vote also will be a test of the strength of Islamist parties, which have gained influence in Libya and other nations following the ouster of authoritarian regimes run by strongmen like Gadhafi and Egypt's Hosni Mubarak. Groups vying for power range from the politically savvy Muslim Brotherhood to the ultraconservative Salafis and former jihadists.

Late Thursday, just before a 24-hour pre-vote ban on campaigning went into effect, supporters of the Justice and Construction party co-founded by the Muslim Brotherhood marched through the streets of Tripoli carrying the party's flags. The Alliance of National Forces, led by secular-leaning former premier Mahmoud Jibril, paraded in cars plastered with party posters. The National Front, which descends from a Gadhafi-era opposition movement, lit the sky over the capital with fireworks.

A day earlier, the former rebel commander and former jihadist Abdel-Hakim Belhaj, who co-founded the Homeland, or Al-Watan party, spoke to hundreds of supporters in the heart of Tripoli, endorsing democracy that will serve Islamic Shariah law.

Those four parties are seen as front-runners in a highly unpredictable race.

Libyan observers however say that voters are likely to cast ballots based on personalities they know, rather than ideology. In this conservative, almost entirely Muslim country, nearly all politicians accord Shariah a role in the constitution.

The NTC also decreed Thursday that the new constitution will definitely give a role to Islamic law, a move that appeared intended at preventing parties from turning the race to an Islamist-versus-secular contest.

Some 2.8 million voters, out of more than three million eligible, have registered for the polls. New parliamentary elections are to be held in 2013, after the constitution is drafted and approved in a referendum.

Observers expect that no party is likely to win an outright majority and the shape of the final government will likely depend on post-election alliances.

"We might see the Justice and Construction party striking alliance with Jibril's party, or we might see all Islamists forming one bloc in parliament," said Mohammed Bu-Sedr, a political prisoner during the Gadhafi era who now serves as adviser to the NTC's head and is running as an independent candidate in Benghazi.