Sri Lanka's former wartime defence chief Gotabaya Rajapaksa has won a presidential election that has split the country along ethnic lines.

Official results showed Mr Rajapaksa took 52.25% of the vote. His rival Sajith Premadasa had already conceded.

Analysts say Mr Rajapaksa was the clear victor in Sinhalese majority areas while Mr Premadasa scored better in the Tamil-dominated north.

The election is Sri Lanka's first since a deadly terror attack in April.

Militants linked to the Islamic State group targeted churches and high-end hotels across the island on Easter Sunday, killing more than 250 people.

Mr Premadasa publicly conceded when partial results showed Mr Rajapaksa was certain to emerge the winner.

In a statement on Twitter, Mr Rajapaksa made a call for national unity saying "all Sri Lankans are part of this journey".