Mahinda Rajapaksa was sworn in Sunday as Sri Lanka's prime minister after a landslide victory for the ruling party in Wednesday's parliamentary elections, officials said.
Monks chanted prayers as the 74-year-old was sworn in for another five-year term before President Gotabaya Rajapaksa, his younger brother, at a historic Buddhist temple in Kelaniya, 10 kilometres from the capital.
The ruling Sri Lanka Podujana Party (Sri Lanka Peoples' Party) won 145 seats (59 per cent of the vote) and obtained the support of minor parties to seal a two-thirds majority of 150 members in the 225-seat parliament.
The main opposition, the United People's Front (SJB), trailed far behind with only 24 per cent of the votes and 54 seats.
The results have bolstered the powers of both Rajapaksa brothers.
Prime Minister Rajapaksa served two terms as the country's president from 2005 to 2015.
He then returned to parliament after a constitutional amendment by the former government limited presidential terms to two, effectively stopping him from contesting for a third term.
He has also served as prime minister on three previous occasions.
The victory of the ruling party is a boost for President Rajapaksa, who took office in November last year, as he now has a strong parliamentary majority to pass legislation and any amendments to the constitution.