NEW YORK - Prime Minister Mahathir Mohamad said he expects to remain as Malaysia's leader for some three years, just a week after MP Anwar Ibrahim indicated the premier would step down after roughly two years.

"I promise that I would step down before the next election and give way to another candidate," Tun Dr Mahathir told a dialogue at the US Council on Foreign Relations in New York on Thursday (Sept 26), as reported by Bernama news agency.

"So, I may have at the most three years perhaps," he added. The next general election is slated in 2023.

Dr Mahathir, 94, said these days he works "very tough" 18-hour days.

"This is because I don't have much time" before stepping down, Bernama quoted him as saying.

The handing over of the premiership from the seventh prime minister to the eighth has sometimes roiled Malaysian politics since the four-party Pakatan Harapan (PH) alliance unexpectedly won federal power in the May general election last year.

In an informal agreement set before the polls that PH had expected to lose, Dr Mahathir was given the mandate to lead as prime minister before handing the baton to Datuk Seri Anwar, 72, who was then in jail.

Dr Mahathir leads the pro-Malay Parti Pribumi Bersatu Malaysia with 27 seats in Parliament, and Mr Anwar is president of Parti Keadilan Rakyat with 50 seats, the biggest number of parliamentary seats.

Adding to tensions between supporters of the two leaders, Datuk A. Kadir Jasin - who is Dr Mahathir's media and communications adviser - said on Monday that there were no PH documents before the 2018 election mentioning a time frame for the handover.

"There were five promises agreed to by Harapan leaders - which is Tun M (Mahathir) will be Harapan chairperson, Tun M will lead Harapan in the 14th general election, Tun M will become prime minister, seek a royal pardon for Anwar and pass the (prime minister) position to Anwar," Mr Kadir was quoted as saying, when speaking to university students in Terengganu on Monday.

"However, the agreement, the documents do not state a date. The year 2020, 2030 or 2050, the date was not stated," he said.

Mr Anwar, in an interview with Bloomberg Television on Sept 18, said he expects to become prime minister around May 2020, two years after PH won power.

"There's an understanding that it should be around that time, but I don't think I should be too petty about the exact month," he said in the interview.