Malaysian ex-leader Mahathir Mohamad, 92, said Thursday he expects to be sworn in as prime minister soon, quelling concerns around the succession after his stunning win over the scandal-plagued coalition that has ruled for six decades.

In a huge political upset, Mahathir's opposition alliance ended the hold on power of the Barisan Nasional (BN) coalition, which has governed Malaysia uninterrupted since its birth as an independent country in 1957.

It capped a dramatic political comeback for Mahathir, who previously ruled the country with an iron fist for 22 years and came out of retirement to take on Prime Minister Najib Razak after the leader became embroiled in a massive corruption scandal.

Mahathir was expected to be sworn in at 5:00 pm (0900 GMT), and will be the world's oldest leader.

In a volte-face, Mahathir had thrown in his lot with an alliance of opposition parties he crushed while in power, which included jailed opposition icon Anwar Ibrahim -- his former nemesis.

Mahathir has pledged to get Anwar, who is due out of jail in June, a royal pardon and eventually pass the premiership to a man who is one of the country's most charismatic and popular politicians.

However concerns mounted about the transfer of power Thursday morning after Mahathir was not inaugurated by the king, as had been widely expected.

He said there had been some delays due to confusion over certain parts of the constitution but this had now been cleared up, and called for his inauguration to take place by 5:00 pm.

"We expect today for me to be sworn in as prime minister," he told a press conference.

"There is an urgency here. Currently there is no government in Malaysia."

His speech came after Najib, in his first public comments since his shock loss, said he accepted the people's will -- but did not give a clear concession, and said that it was up to the king to decide on the prime minister as no single party had won a clear majority.

"I accept the verdict of the people and BN is committed to the principles of democracy," said Najib, looking shattered.