The first elections in Sri Lanka since the civil war ended in May are being held in the Tamil-dominated north.
The government has described the votes in Jaffna and Vavuniya, as well as in the southern province of Uva, as a step towards normality in the country.
However, journalists from independent media have been banned from going to the northern towns to cover the voting.
On Friday, Sri Lanka's defence ministry said it had arrested the new head of the defeated Tamil Tiger rebel group.
Selvarasa Pathmanathan was detained abroad and was being questioned in Sri Lanka, it said. The rebels have confirmed the arrest.
Voters in the two towns of Jaffna and Vavuniya in the Tamil-dominated north will have to choose between a broad government coalition, the main opposition party, and an umbrella group supportive of the Liberation Tigers of Tamil Eelam (LTTE).
There are smaller parties too, including a moderate Tamil one contesting Jaffna.
The government continues to tighten its grip on society despite its victory in May, and has banned all journalists other than the state-controlled media from the towns.
But there will be some electoral monitoring by human rights groups.
Life is far from normal in northern Sri Lanka. Near Vavuniya, more than a quarter of a million Tamil refugees are stuck in government-run camps which they are not allowed to leave.
Refugees in the north were asked to apply to vote if eligible. But only 6,000 have registered, mostly in camps away from Vavuniya.
As a result of its victory in the civil war, the government is very popular in the Sinhalese-dominated south and it hopes to do well in the north, too, with a coalition including some parties said to be attached to anti-LTTE Tamil paramilitaries.
Some of the government's opponents have complained they have been obstructed or intimidated in their campaigning.