KUALA LUMPUR - Being Malaysian prime minister for the second time is "frightening" and a "much more difficult task", said Tun Mahathir Mohamad.

When he took over in 1981, he told The Edge Malaysia in an interview, he was just taking over from the same Barisan Nasional government.

Today, the Pakatan Harapan (PH) coalition has taken over the federal government for the first time and he needs to shape it with a new manifesto.

"It is frightening! It is a much more difficult task (than in 1981). I have to sit down and be briefed.

"And then I have to fill in posts with people I don't know. It takes a lot of time. I don't know about destiny, but I was practically forced to come back.

"So, I don't know if it's destiny or not but I have a duty," Dr Mahathir told the business week.

Dr Mahathir was Malaysia's prime minister for 22 years before stepping down in 2003. He was replaced by Tun Abdullah Badawi, and he toppled premier Najib Razak in the May 9 general election.

"People are not happy with the previous government. They think many things were done wrong and we have to dig out these wrong things," he told The Edge.

The new PH government will effectively abolish the unpopular 6 per cent goods and services tax on June 1.

PH also promised to abolish toll collection in its election manifesto.