KUALA LUMPUR - Mahathir Mohamad, 92, a former Malaysian prime minister who led the opposition to achieve a stunning victory in the general election, took the oath of office on Thursday night, becoming the world's oldest government leader.

Mahathir won the election after his coalition Pakatan Harapan secured 113 seats out of the 222 seats at the parliament's lower house, unseating the Barisna Nasional coalition, which has run the country for more than 60 years and of which Mahathir used to serve as the chairman.

TV live-broadcast showed that Mahathir, wearing traditional malay attire, pledged to serve the country and the people well.

He was accompanied by his wife Siti Hasmah Mohamad Ali and other leaders in the opposition alliance, including Wan Azizah Wan Ismail, whom Mahathir pledged to tap as the deputy prime minister.

The ceremony, held at the national palace, was witnessed by Malaysia's head of state Sultan Muhammad V.

A statement released by the royal palace ahead of the ceremony said the king Sultan Muhammad V invited Mahathir to form the next federal government.

The royal palace also refuted allegations that the king delayed the appointment of Mahathir as the new prime minister, saying that he strongly supports and respects the democratic process.

The appointment of Mahathir as prime minister added more optimistic sentiments and jubilance to the country, with many Pakatan Harapan supporters taking to the street, holding flags and honking horns.