Mahathir Mohamad has been sworn in as Malaysia’s seventh prime minister following his stunning election victory over the coalition that has ruled the Southeast Asian nation for six decades since independence from Britain.

Malaysia’s constitutional monarch, Sultan Muhammad, administered the oath of office just before 10pm local time on Thursday, in a ceremony carried live on state television from the palace.

Mr Mahathir, 92, is the oldest elected leader in the world.

Hundreds of Malaysians were lined up on the road leading to the palace, waving party flags and cheering. The Election Commission announced the result long before dawn and there was some consternation in the capital over the time taken to swear in the new prime minister.

Mr Mahathir ruled Malaysia with an iron fist from 1981 to 2003. He came out of retirement to take on his former protege, Najib Razak, who was prime minister for nearly a decade.

Mr Mahathir’s alliance of four parties trounced Najib’s Barisan Nasional (National Front), the first time it had ever lost an election.

Earlier on Thursday, Mr Najib appeared to raise doubts that Mr Mahathir would immediately take office because no single party had won a simple majority of seats in the 222-member parliament, and it would be up to the monarch to decide.

Official results showed that Mr Mahathir’s coalition won 121 seats, comfortably more than the 112 required to rule. But it has not been formally registered as an alliance.

In jubilant mood and cracking jokes, Mr Mahathir dismissed any doubts he would be prime minister. He said he had been assured of support from a raft of parties that would give his government 135 members of parliament.

Mr Najib’s BN coalition won 79 seats, a collapse from the 133 it won in the 2013 election, which was itself the coalition’s worst poll performance ever at the time.

Few had expectedMr  Mahathir to prevail against a coalition that has long relied on the support of the country’s ethnic-Malay majority.

However, he joined hands with jailed political leader Anwar Ibrahim, his one-time deputy he famously fell out with in 1998, and together their alliance exploited public disenchantment over the cost of living and a multibillion-dollar scandal that has dogged Mr Najib since 2015.

Mr Mahathir said that one of his first actions would be to seek a royal pardon for Mr Anwar. Before the poll he had promised to step aside once Anwar was free and let him become prime minister.

Mr Anwar’s wife, Wan Azizah Wan Ismail, was sitting next to Mr Mahathir at his news conference. Under an agreement with Mr Mahathir, she is to be deputy prime minister.

Mr Mahathir and Mr Najib were once allies but they clashed over a scandal around 1Malaysia Development Berhad (1MDB), a state fund from which billions of dollars were allegedly siphoned off.

Mr Mahathir had vowed to investigate the scandal if elected and bring missing funds back to Malaysia. On Thursday, he said that if Mr Najib had done anything wrong he would “face the consequences”.