Indonesia's only province ruled by Islamic law went to the polls Monday to elect its powerful governor, testing a fragile peace following a 30-year war by separatist rebels.

The elections in Aceh were the second since the province suffered 170,000 fatalities in the Asian tsunami of 2004, and since the war against Indonesian rule ended in 2005, having claimed 15,000 lives.

Voters cast their ballots for governor -- the top post in the province -- as well as 17 district heads and deputies, with official results expected in mid-April.

Irwandi Yusuf, the 51-year-old incumbent who was elected in December 2006, is seeking a second five-year term as governor, with his main challenge coming from the powerful Aceh Party's Zaini Abdullah, 71.

A respected local survey group said that a quick count from 350 randomly chosen polling stations -- that did not reflect official results -- showed that Abdullah would win.

At the village of Ulee Lheue on the outskirts of the capital Banda Aceh, voters cast their ballots at the Baiturrahim Mosque, the only structure in the fishing community that survived the tsunami.

"We want a leader who will look after us," said Bursiadi, a 38-year-old fisherman who lost 20 family members and was himself taken for dead until waking up in a body bag.

"The tsunami was the lowest point for us all and we want to put that behind," said Bursiadi, who like many Indonesians goes by one name.

Only 415 people out of the community of 6,000 villagers survived the tsunami.

Officials said the vote passed off peacefully, despite outbreaks of violence in the run-up to the polls amid tensions between former rebels.

The respected Indonesia Survey Circle (LSI) said a quick count showed that Abdullah and his running mate for deputy would come out the winners.

"Based on results of the quick count -- which is a prediction and not official -- pair number five of Zaini Abdullah and Muzakir Manaf won 54.4 percent," the LSI's Chandra Hendarnoto told reporters hours after polls closed.

Aceh, on the western edge of the scattered Indonesian archipelago, enjoys broad autonomy and is an anomaly in a country where most of the 240 million people practise a moderate form of Islam.

Alcohol is freely sold in the rest of Indonesia, the world's most populous Muslim-majority nation, but it is banned in Aceh. In some of the province's regions, women are forbidden from wearing tight trousers.

Gamblers and imbibers are publicly caned. Debate still churns in Aceh over whether adulterers should continue to be publicly flogged, or stoned to death.

"I want Islamic sharia in place, but peace is most important," said Mariam, a 45-year old food vendor in Banda Aceh. "I had to stay indoors most times during the conflict. Now, I can sell food and walk around freely," she added.

Much election tension has centred around Yusuf, who like many other politicians had been a rebel with the now-defunct separatist Free Aceh Movement (GAM), and his feud with the Aceh Party.

The Aceh Party was created by GAM in 2008 and is backing Abdullah.

"The election is clearly a competition between Irwandi... and the Aceh Party," said Jakarta-based analyst Jan Lepeltak.

Candidates need more than 30 percent of the vote for an outright win, and Hendarnoto said his group had counted about 95 percent of the ballots at 350 polling stations, out of 9,786 booths province-wide.

He said Yusuf and his running mate came second with 29.88 percent, adding that the count had a margin of error of plus or minus one percent.

The elections are seen as a test for a fragile peace following the decades-long insurgency.

Divisions among the former GAM leaders have grown since the 2005 agreement with Indonesia that ended the war, with Yusuf saying he had survived an assassination attempt last month.

The Aceh Party, which dominates the regional parliament, has been bitterly opposed to Yusuf for running as an independent.

Authorities say that a series of fatal shootings and at least 57 cases of intimidation were reported in the run-up to the poll, many involving supporters of Yusuf and Abdullah, raising fears of unrest in the aftermath of the vote.

More than three million residents were eligible to vote.