COLOMBO: Prime Minister Mahinda Rajapakse is set to become Sri Lanka's next president with one of the smallest majorities in the country's electoral history, officials said Friday.

The vote took place on Thursday amid a boycott by the rebels in the northern and eastern parts of the country, with relative calm in the rest of the island.

Representing the ruling United People's Freedom Alliance (UPFA), Rajapakse was ahead by more than 162,309 votes against leading rival Ranil Wickremesinghe, head of the United National Party (UNP).

Rajapakse had 4.5 million votes (50.25 percent of valid ballots counted), with Wickremesinghe at 4.4 million votes (48.4 percent of valid votes), with 150 of 160 electorates counted.

Rajapakse did well mainly in southern Sri Lanka and in rural areas, while Wickremesinghe's strongholds were in urban areas and the eastern province, where presidential voting was partially affected by a boycott call by the Liberation Tigers of Tamil Eelam (LTTE).

The rebel boycott affected voting mainly in the northern Jaffna peninsula, where less than one percent of the electorate appeared to have voted.

The boycott mainly affected Wickremesinghe, who was tipped to secure more votes in the northern province, where civilians have benefited from the ceasefire that he implemented as prime minister after the 2001 parliamentary elections. He was defeated in last year's parliamentary elections.

Results from the remaining 10 electorates were expected before midday Friday. The winner needs to obtain more than 50 percent of valid votes to capture the presidency.

Officials said Rajapakse was set to be elected president with the smallest ever majority in a presidential election since the system was introduced in 1978.

Tamil rebels making use of their front organisations told Tamil voters not to turn out, contending that the outcome of the presidential election would not help to resolve problems in the northeastern part of the country.