Malaysian police officials said Wednesday that they will question former premier Mahathir Mohamad for making allegations against Prime Minister Najib Razak. Mahathir made the comments, demanding the removal of Najib, at a demonstration attended by tens of thousands of people in Kuala Lumpur on Sunday.

“We will call him (Mahathir). He has made speeches and accusations,” Khalid Abu Bakar, national police chief, said, according to a local news website, cited by Agence France-Presse (AFP), adding: “Among them, he claimed UMNO (the ruling United Malays National Organization) leaders had taken bribes, so we want to find out more.”

Mahathir, who was Malaysia’s longest-serving prime minister, has accused Najib of bribing UMNO leaders in order to remain in power with their support and avoid corruption charges. However, reports Wednesday said it was not clear if Mahathir, who held the prime minister's post for 22 years from 1981 until 2003, and still remains influential in the ruling party, would face any charges.

"The only way for the people to get back to the old system is for them to remove this prime minister," Mahathir reportedly said in Kuala Lumpur, adding: "And to remove him, the people must show people's power. The people as a whole do not want this kind of corrupt leader."

The organizers of the anti-government rally also said, according to AFP, that they have been asked to report to police on Wednesday.

Protesters began demanding Najib’s resignation after a report by the Wall Street Journal in July claimed that investigators were probing $700 million in Najib’s personal account, which he allegedly transferred from the indebted state-investment fund 1Malaysia Development Bhd (1MDB). Najib, who established 1MDB in 2009, was also accused of mismanaging the fund, which has a debt of $11 billion.

Najib has denied the accusations, claiming that the money in his account was deposited as donation from the Middle East. He also threatened to sue the Journal over the report.