The scandal of 1MDB is a "non-issue" twisted by former prime minister Dr Mahathir Mohamad in order to elevate his son Mukhriz Mahathir to prime ministership.

Former DAP leader Tunku Abdul Aziz Ibrahim made the claim today at a press conference at Eastin Hotel in Kuala Lumpur.

"In hindsight, 1MDB was a non-issue, stirred and twisted by Mahathir to serve his political agenda of bringing down a constitutionally-elected prime minister as part of a larger plan to put his unremarkable son Mukhriz as a candidate for the nation's highest public office," he said

Mahathir had been vocally critical of his former protege Prime Minister Najib Abdul Razak and the troubled state fund 1MDB since last year.

1MDB is under investigations in several countries, including the US, Switzerland and Singapore.

Najib had consistently denied wrongdoing in this matter and was exonerated by attorney-general Mohamed Apandi Ali earlier this year.

Tunku Abdul Aziz also urged Mahathir to "come clean" on how his three sons, Mukhriz, Mokhzani and Mirzan, accumulated vast wealth in a short period of time.

"Mahathir must come clean on this and other instances of corruption linked to his name if he is to assume a leadership role in public or political life ever again." 

He also questioned the sudden blossoming of an "unlikely partnership" between DAP parliamentary leader Lim Kit Siang and Mahathir, who were previously on opposite ends of the political divide.

Lim, he said, used to be one of the most vocal and ardent critics of human rights suppression and corruption during Mahathir's reign as prime minister.

"This is why it came as a complete surprise to him when Lim started cooperating with Mahathir, whom Tunku Abdul Aziz claimed fathered "grand corruption" in the country.

"Has the promise of personal gain so blinded him to the recklessness of his act that he (Lim) is prepared to sell his soul to the devil?

"Mahathir is for Mahathir and the devil take the hindmost," he warned.

At today's Pakatan Harapan Convention in Shah Alam, Mahathir, who is Parti Pribumi Bersatu Malaysia chairperson, was one of the speakers.

He insisted that Bersatu has the intention to be with other parties in Harapan, despite reports that the party's pro-tem president Muhyiddin Yassin was against the unification of Pakatan Harapan and Bersatu.