KUALA LUMPUR--Anwar Ibrahim, in line to take over Malaysia's leadership, will be called in for questioning over allegations that he had sexually assaulted a former male aide, police said on Wednesday.

Anwar has denied the accusation by the aide, Muhammed Yusoff Rawther, describing it as "politics at its worst."

Muhammed Yusoff is being represented by a lawyer who counts Prime Minister Mahathir Mohamad among his clients. On Tuesday, Mahathir promised to hand over power to rival-turned-ally Anwar despite the latest allegations against him.

Muhammed Yusoff said last week that Anwar had attempted to force him to have sex in September 2018.

Police recorded Muhammed Yusoff's statement on Monday, criminal investigations department director Huzir Mohamed said in a statement.

"Statements from Anwar Ibrahim and several related witnesses will be taken as soon as appropriate appointment times are set," Huzir said.

A spokesman for Anwar said police had not contacted him yet.

Anwar has spent nearly a decade in jail on two separate counts of sodomy and for corruption, charges that he and his supporters maintain were aimed at ending his political career.

Muhammed Yusoff's lawyer Mohamed Haniff Khatri Abdulla denied a conflict of interest in taking on a case against the prime minister's planned successor.

"The prime minister is still my client but that does not mean I should not take on cases just because they involve his ministers or people in his administration," Mohamed Haniff told Reuters.

"I did not speak to (Mahathir) before taking on this case, but we did talk about it afterwards. He was surprised but he understood."

Mahathir's office did not immediately respond to a request for comment. Anwar's spokesman declined comment.

Mohamed Haniff denied charges of a political conspiracy in the allegations against Anwar, saying Muhammed Yusoff stood by his statement.

"It's time to let the police investigate," he said.

Same-sex acts are illegal in Muslim-majority Malaysia, and carry penalties of up to 20 years in jail if convicted.

A former deputy prime minister, Anwar was first sacked and then jailed in 1999 during Mahathir's first 1991-2003 tenure as prime minister.

Mahathir and Anwar mended fences in 2016, joining forces to lead the opposition to an unexpected election victory last year.