Over 15 million voters are eligible to vote in the election being held under electoral districts-based proportional representation system.
Sri Lankans began voting on Monday in parliamentary polls with former strongman Mahinda Rajapaksa eyeing a political comeback as prime minister months after being toppled as president by Maithripala Sirisena.
Sirisena has vowed not to make Rajapaksa premier even if his United People's Freedom Alliance wins a majority.
Polls opened at 07:00 local time and will close at 16:00.
"Island wide 12,314 polling stations and 1,600 counting centres have been set up for today's election. Around 195,000 officers are involved in election duty. Out of them 125,000 officials are deployed at polling stations, while another 70,000 officials are deployed at the counting centers," Deputy Elections Commissioner M M Mohammed said.
“The preferential vote results would be announced later in the night on Tuesday,” he said.
The election to the 225-seat national parliament promises a close battle between the United National Party of Prime Minister Ranil Wickremesinghe and the UPFA of President Sirisena.
Over 15 million voters are eligible to vote in the election being held under electoral districts-based proportional representation system.
196 members will be elected from districts while 29 will be appointed based on the national proportion of votes polled by each party.
To have a working majority government, 113 seats are needed in the National Assembly.
The rivalry between Wickremesinghe and Sirisena is limited to party positions they hold as the former's support helped the latter become president in January by defeating Rajapaksa.
However the real challenge to the UNP comes from former president and Sinhala strongman Rajapaksa.
Rajapaksa, 69, forced himself into the UPFA reckoning to contest the parliamentary poll, an action unprecedented for a former president of the country.
Sirisena was not in favour of granting Rajapaksa a party ticket but his party allies have defied his wishes.
Accusing Rajapaksa of alienating Tamil and Muslim minorities from the Sri Lanka Freedom Party, Sirisena had last week asked his predecessor not to create divisions in the party.
Sirisena was Rajapaksa's health minister until he came forward as the opposition unity candidate to challenge the then president last year. He then handed Rajapaksa a shock defeat in the polls.
Poll monitoring groups have already dubbed it as the fairest election campaign in the island in recent times with a minimum number of election law violations.
Image: Former President Mahinda Rajapaksa with Sri Lankan army officers in 2011.
