Jaffna, Sri Lanka: Sri Lankan Tamils went to the polls in large numbers on Thursday, defying what the opposition said were attempts to discourage voting in the heavily militarised Jaffna peninsula, where President Mahinda Rajapakse is widely disliked

Witnesses heard a loud blast as voting got under way in the northern region, which was on the front line of a decades-long civil war that only ended in 2009. "It was a loud explosion clearly designed to discourage people from voting," Tamil lawmaker Easwarapatham Saravanapavan told AFP.

"There was a large crowd of people waiting to vote when this happened." Rajapakse is deeply unpopular in Tamil-dominated Jaffna for orchestrating a military campaign against the Tamil Tiger separatist rebels in which thousands of civilians were also killed.

Tamils are Sri Lanka's biggest minority, accounting for 13 percent of its 15 million voters, and could decide the election if the majority Sinhalese vote is split between Rajapakse and his main opponent. The main Tamil party, the Tamil National Alliance (TNA), has thrown its weight behind the opposition candidate Maithripala Sirisena.

His supporters last week accused the government of deploying thousands of troops to Tamil-majority areas as part of a strategy to intimidate voters. Nonetheless, Saravanapavan said people were eager to cast their ballots across the peninsula, where over 700,000 Tamils are eligible to vote in the closely fought election.

"I was the first to vote at the Navalar polling booth in Jaffna," Saravanapavan said. "As I stepped out, there were nearly 100 people in the queue." He said a senior TNA party worker had received a death threat on Wednesday night, but had not been deterred from voting.

Tamil translator S. Sebanayagam said he had to wait in line to cast his vote. "There were lots people ahead of me, including some very elderly people who seemed keen to vote," Sebanayagam told AFP after casting his ballot in his village in Jaffna.

The Campaign for Free and Fair Elections, a private monitoring group, said voter turnout was exceptionally high in most parts of the country, including the former war zones. "We are seeing heightened enthusiasm among minorities," CaFFE chief Keerthi Thennakoon told AFP.

"Unlike in the past, many of them decided to go to the polls early. There is very brisk polling." The Tamil Tigers ran Jaffna as a de facto state for nearly five years until they were dislodged in 1995 and the area has been heavily militarised since the war ended in 2009.

Jaffna school teacher K. Loganathan, 74, said he was voting for "change".