COLOMBO, Sri Lanka -- Gotabaya Rajapaksa, a former defence official revered by Sri Lanka's ethnic majority for his role in ending a bloody civil war but feared by minorities for his brutal approach, declared victory Sunday in the nation's presidential election.

Sri Lanka's ruling party presidential candidate, Housing Minister Sajith Premadasa, conceded defeat to Rajapaksa, saying he would honour the decision of the people.

Rajapaksa, the campaign front-runner and former defence secretary under his brother, ex-President Mahinda Rajapaksa, pledged to restore security to the Indian Ocean island nation still recovering from Islamic State-inspired attacks last Easter.

Rajapaksa announced his candidacy shortly after the terrorist attack that killed 269 people, faulting the government for intelligence lapses and letting the security sector falter.

His victory in Saturday's vote marks the return of a family ousted from power in 2015 elections amid constant reports of nepotism, skimming off development deals with China and alleged human rights violations during the end of the decades-long war with the Tamil Tiger rebels in 2009. The election also mirrors the global trend of populist strongmen appealing to disgruntled majorities amid rising ethno-nationalism.

"As we usher in a new journey for Sri Lanka, we must remember that all Sri Lankans are part of this journey. Let us rejoice peacefully, with dignity and discipline," Rajapaksa tweeted.

Supporters outside Rajapaksa's home on the outskirts of the capital Colombo hugged and cheered, some clutching bouquets of flowers.

About 15 million people were eligible to vote, and Sri Lanka's Election Commission estimated 80% turnout after polls closed.

Flanked by Buddhist monks at campaign events, Rajapaksa focused his message on Sri Lanka's majority Sinhala Buddhist population, who comprise about 70% of the island's citizens. The second-largest group are ethnic Tamil Hindus at 12.6%, while 10% are Muslims and 8% are Christian.

He accepted support from Buddhist nationalist clerics who demanded the resignation of Muslim Cabinet members and governors they said were interfering with the investigation of the Easter attacks.

The Muslim politicians temporarily stepped aside.

The campaign said Rajapaksa's swearing-in ceremony would take place at Anuradhapura, a city about 200 kilometres (124 miles) from Colombo and the seat of the first Sinhalese kingdom known for a sacred tree that is said to be the southern branch of the Bodhi tree in India under which Lord Buddha attained enlightenment.

Though counting continued, the preliminary result reflected voting along ethnic lines, showing "a badly polarized country" that will embolden right-wing Buddhist clerics, said Kusal Perera, a political analyst and independent journalist.

"A Sinhala Buddhist theocratic state has been given a people's mandate now," he said.

Premadasa swept the majority Tamil and Muslim districts in the country's north and east, winning as much as 80% of the vote. In majority ethnic Sinhala areas, Gotabaya secured around 60%.

Sinhala Buddhists votes usually don't vote as a bloc, unlike Sri Lankan minorities who have supported whatever party espoused policies comparatively favourable to them.

Rajapaksa's victory will also be a blow to the post-civil war reconciliation process and truth-seeking on alleged wartime abuses by both government troops and the Tamil Tiger rebels. In the lead up to the election, Rajapaksa said that he would not honour a United Nations human rights resolution to investigate alleged abuses.

"He has won the war, but Sri Lanka is yet to win the peace and 10 years after, this is how the north and east reacts to the war victor," said M.A Suanthiran, lawmaker and spokesman for Tamil National Alliance, the country's main Tamil party.

Rajapaksa pledged to appoint as prime minister his brother Mahinda Rajapaksa, who was briefly installed as prime minister last year, when outgoing President Maithripala Sirisena fired the sitting prime minister, Ranil Wickremesinghe, over political differences. The Supreme Court ruled Sirisena had acted unconstitutionally, and restored Wickremsinghe to power.

Gotabaya Rajapaksa has also promised to release people detained for running an abduction ring for money in the pretext of counterterrorism, leading some to fear that the ethnic tensions that fueled the Tamil struggle for an independent state will only grow during his administration.

During the war that ended in 2009, Gotabaya Rajapaksa was accused of persecuting critics and overseeing what were called "white van squads" that whisked away journalists, activists and Tamil civilians suspected of links to the Tamil Tigers. Some were tortured and released, while others simply disappeared.

The Rajapaksa brothers are also accused of condoning rape and extrajudicial killings and deliberately targeting civilians and hospitals during the war. They deny the allegations.

The Rajapaksas did not lift emergency law even after the war ended, curtailing civil and media freedoms. Mahinda Rajapaksa's government accepted Chinese loans for white elephant projects in the family's home district of Hambantota, including to build a big commercial airport that has never been used.

Battling one of Asia's highest debt-to-GDP ratios, Wickremesinghe's government signed in 2017 a 99-year lease of the Chinese-built Hambantota port to a Chinese company, fueling public consternation over the loss of Sri Lanka's sovereignty. The outgoing government also re-established ties with neighbouring India and the United States, both of whom have large stakes in Sri Lanka as a buffer against China.

Rajapaksa will inherit a tourism-dependent economy still recovering from the blasts, the first attack in Sri Lankan history targeting foreigners.