Dr Mahathir is Malaysia's 7th Prime Minister

Dr Mahathir Mohamad was sworn in as Malaysia's seventh Prime Minister last night, after former premier Najib Razak said he accepted the will of the people that handed Barisan Nasional (BN) a shock defeat, ending the Umno-led pact's six decades in power.

Following press conferences in which he asserted that his Pakatan Harapan (PH) coalition had clearly won Wednesday's vote, Dr Mahathir was granted an audience with the King, Sultan Muhammad V, at 5pm.

But it was only five hours later that he was officially declared PM, having had to wait while leaders of the four parties in his coalition were interviewed by the King, who then invited the 92-year-old to form the next government and add to his 22 years of leading the country.

PH and its ally Parti Warisan Sabah won 121 seats in the 222-seat federal Parliament in the May 9 general election, while BN secured 79 seats, in results that were ready by the early hours of yesterday.

But, the palace received official results from the Election Commission at 2.45pm .

The delay raised questions among the public, and on social media, prompting the Comptroller of the Royal Household Wan Ahmad Dahlan Ab Aziz to say in a statement last night: "Istana Negara strongly refutes any allegation that His Majesty... delayed the appointment of Tun Dr Mahathir as Prime Minister. His Majesty looks forward to working with Tun Dr Mahathir and his administration for the betterment of our nation and all its people."

Confusion had erupted after messages went viral about a 9.30am swearing in, which the Palace had to deny.

Later, it was expected that Dr Mahathir, now the world's oldest head of government, would be sworn in during his 5pm audience, which instead ended up being a test of his control of Parliament.

Speaking to reporters at a press conference after the ceremony, Dr Mahathir said the delay was "unavoidable because of certain official processes which we have to go through".

"I would like to thank the people who supported us," he said.

He also gave the assurance that his administration would be business-friendly.

"Malaysia has been a trading nation. You don't quarrel with your market," he said.

Having defeated the long-ruling BN, which he headed until 2003, and then left in 2016 after calling for Datuk Seri Najib's ouster over the scandal at state-owned fund 1MDB, Dr Mahathir had earlier asked to be sworn in "as soon as possible" after his PH had crossed the threshold of a simple majority of 112 seats by early yesterday morning.

After Dr Mahathir was sworn in, Mr Najib said on Twitter he had sent his congratulations to his successor. "I am prepared to help in a smooth transition of power," he added.