Dr Mahathir, who has campaigned for Najib to be ousted as Umno president and prime minister, said Najib should face action for having sabotaged democracy.

“As long as Najib remains, Malaysia will not be democratic,” he wrote in his blog on Friday.

“Even worse, Malaysia will be ruled by a dictatorship with no regard for the law,” said the former premier who himself was criticised as being dictatorial and having undermined democracy during his 22-year rule as prime minister.

Dr Mahathir responded to Najib’s criticisms that the actions to oust him were undemocratic by saying that “anywhere else around the world, a democratic leader would be ousted before the grand expose”.

Dr Mahathir also accused Najib of having a hand in having forced Najib’s predecessor Abdullah Ahmad Badawi out of office midway through his term. (Abdullah resigned in 2009, a year after the 2008 general election in which opposition parties gained control of five states.)

He said Najib had made “baseless” complaints about undemocratic means being used to oust him, and gave the examples of Tony Abbot of Australia, who resigned when his party chose a new leader, David Cameron of Britain, who stepped down after losing the Brexit referendum, President Lula of Brazil, who was suspended by the Senate to avoid the possibility of him disrupting investigations against him, and US President Richard Nixon who left because of the Watergate scandal.

“This is proof that democracy is progressing while what is happening now is that Najib, as the PM, has already rejected democracy,” Dr Mahathir said.

He reiterated his frequent accusations that Najib had undermined the separation of powers between the legislative, judiciary and executive which he said was “something that contradicts democracy”.