Former prime minister Dr Mahathir Mohamad has told Malaysian Anti-Corruption Commission's (MACC) Tunku Abdul Aziz Tunku Ibrahim to remain silent if he cannot do anything about the beleaguered 1Malaysia Development Berhad (1MDB).

This is after Tunku Abdul Aziz ( photo ) - an MACC board member - said MACC was prepared to investigate Penang-born billionaire Jho Low and the prime minister's stepson Riza Aziz if Mahathir were to lodge a report with the graft-buster agency.

"Actually, the report has already been made by other quarters but no one initiated any investigation.

"Instead, the person who made the report was made a bankrupt and his house ransacked," claimed Mahathir.

Mahathir appeared to be referring to former Umno Batu Kawan Umno vice-chief Khairuddin Abu Hassan who was stripped of his position and declared a bankrupt after breaking ranks and launching a tirade against 1MDB.

Jho Low's name has repeatedly emerged in 1MDB's dealings and the billionaire's close links to Riza Aziz has also raised questions about the latter's huge finances following his sudden and meteoric rise as a producer in Hollywood.

Mahathir not advisor

The finance ministry-owned 1MDB has to date accumulated a massive RM42 billion debt.

"If Tunku Aziz is concerned about corruption, then investigate and make reports on the cases. (He can) also prove that I took the government's money.

"If not, then keep quiet," he said.

Mahathir was responding to an article by Tunku Abdul Aziz in The New Straits Times where he accused the then prime minister of refusing to allow criminal proceedings over the 1980s Bumiputra Malaysia Finance Limited (BMF) scandal.

On Wednesday, Mahathir had sarcastically pointed out that unlike Prime Minister Najib Abdul Razak to 1MDB, he was not an advisor to BMF.