Residents in Sri Lanka's war-ravaged east voted for the first time in two decades on Saturday in an election the government hopes will endorse its war to defeat Tamil Tiger rebels.

Voting began hours after a "Black Tiger" rebel suicide squad sank a naval ship in the eastern port of Trincomalee. On Friday, a bomb exploded in a crowded cafe also in the eastern Sri Lanka, killing 12 people an injuring 29.

Security was tightened for the polls in the eastern districts of Trincomalee, Ampara and Batticaloa, where the ruling alliance of President Mahinda Rajapaksa has teamed up with former rebels, whom rights groups accuse of abuses such as child soldier recruitment but are seen as likely winners.

"We want peace soon, I will vote for the people who can bring us peace and send us home soon," said S Chandrasekaran, a 42-year-old farmer who had to flee his home in 2006 when the military began an offensive to drive the Tigers out of the out.

Nearly 1 million people are eligible to vote for 1,342 candidates to fill 35 seats. The vote underpins the government's twin strategy to defeat the rebels using both the ballot box and the current military offensive.

"Week turnout was reported. A total of about 50 percent had cast their vote by 3:00 p.m. (10:30 a.m. British time)," said Kingsly Rodrigo, chairman of People's Action for Free and Fair Elections (PAFFREL), an election monitoring group.

"Various complaints of intimidation, (ballot box) stuffing and chasing polling agents have been reported. We have received about 40 cases of election-related violence."

President Rajapaksa says the poll is crucial to restore democracy to the area, until recently held by the Tigers, and allow development after 25 years of war.

The elections are also part of the government's blueprint for devolution in minority Tamil areas, which it hopes will go hand-in-hand with its push to win the war in which tens of thousands of people have died.

Analysts see the election as a referendum on the government's military strategy against the Tamil Tiger rebels.

Rajapaksa formally scrapped a six-year truce in January. The military quickly stepped up its war against the rebels in their northern stronghold, leading to a surge in casualties on both sides and suicide blasts in the capital.

REFUGEES

"There are 300 people in this IDP (Internally Displaced Person) camp, we have been displaced due to the war since 2006, from Muttur, but still we are in this camp," said V Thivakarasa, a 46-year-old carpenter who has been unable to work since fleeing his home.

"I have not received the polling card to vote. I don't want to vote like an IDP, I want to vote in my own village after settling down there."

The Tigers, who are fighting for an independent homeland for Tamils in the north and east, were driven from the east of the island last year, emboldening the government in its aim to finally crush the rebels and rebuild Sri Lanka's economy.

Saturday's elections follow a smaller, dry-run local poll in the east in March, won by a government-backed party made up of the former rebel fighters, who defected from the Tigers in 2004.

Rajapaksa's government has dismissed concerns about the TMVP, who have also been accused of abductions and extrajudicial killings and have yet to lay down their weapons.

A host of other former militant groups who joined the democratic mainstream in the 1980s are also taking part in the poll.

The main opposition United National Party is contesting with the ethnic minority Sri Lanka Muslim Congress and has accused the government of trying to hand over the east to an armed group, despite their pledge to reinstate democracy in the area.

Provincial council elections are held every five years, but elections in the north and east have been repeatedly postponed because of continued fighting since 1988.