Amid Dr Mahathir Mohamad's tirade against Prime Minister Najib Abdul Razak, a mysterious new NGO has emerged, making exactly the same allegations against the former prime minister.

Citizens for Accountable Governance Malaysia (CAGM) chairperson Mohd Zainal Abidin said billions of ringgit in taxpayers' money went down the drain during Mahathir's tenure as prime minister between 1981 and 2003.

"It is time for Mahathir to come clean on all his financial scandals and answer Malaysians on what went wrong during his administration.

"If he fails to do so, then CAGM, representing a group of concerned Malaysians, will not hesitate to file a citizen’s lawsuit, to the amount of RM50 billion, against Dr Mahathir," Mohd Zainal said in a statement today.

Under Mahathir's time, Mohd Zainal said, there were more than a dozen documented financial scandals that left a "gaping hole in the nation's coffers".

"Malaysia was exposed to multi-billion ringgit bailouts, extravagant projects and wastages under 'outrageously questionable' ventures during Mahathir's reign.

"Malaysians deserve answers from their leaders and this must begin with Mahathir because an estimated RM100 billion was misappropriated under his watch, as widely reported in local and foreign media," he said.

'We will also go after Najib, eventually'

When contacted, Mohd Zainal denied that CAGM was specifically targeting Mahathir, saying that it would also go after Najib, eventually.

"Once we are done with Tun, we will move on to subsequent prime ministers. We are not taking anyone's side.

"We are just not going after Najib immediately because he has done the necessary theatrics by asking the auditor-general and Public Accounts Committee to investigate (1MDB).

"So we will give him some time while we go after Mahathir and (former prime minister) Abdullah Ahmad Badawi," he said.

Mohd Zainal, 45, a lawyer by profession, said CAGM was only set up a month ago and that it has about 2,000 members.

"We realised that all our economic problems are because of embezzlement, corruption and mismanagement.

"What we are doing is going after the source of the problem itself, which is the leadership and the prime ministers," he said.

Mohd Zainal added that the planned suit against Mahathir is mainly to raise awareness of wrongdoings in previous administrations.