Former prime minister Dr Mahathir Mohamad is doubtful the probe on the 1MDB case can be concluded before Bank Negara governor Zeti Akhar Aziz leaves office on April 30.

“I think this is going to be extremely difficult,” he said when asked about Zeti's wish that the central bank's investigation on 1MDB can be completed so that she could leave a clean slate to her successor.

“Of course, this is a good wish on the part of the person who is going to retire,” Mahathir said.

“I left a clean slate, too, when I decided to resign (in 2003),” he added.

Last year, Bank Negara had proposed that the public prosecutor take appropriate enforcement action against 1MDB. However, the Attorney-General's Chambers later cleared 1MDB of any wrongdoing.

On Oct 9, 2015, the central bank revoked its prior approval for 1MDB to transfer US$1.83 billion (about RM7.5 billion) overseas and instructed 1MDB to repatriate the amount to which 1MDB claimed it was unable to do as the money was either spent or earmarked for debt transfer.

Zeti later said Bank Negara would check on 1MDB's claim and yesterday said that the verification process had yet to be concluded.

Meanwhile, Mahathir brushed off accusation that his criticism of Prime Minister Najib Abdul Razak had impacted the economy.

“It is the behaviour of the government, its policies and scandal that have affected the economy.

“The foreign press, too, had been giving full-page reports on what Najib had been doing. Of course, this would affect the economy. It is not what I said. It is what what Najib does,” he said.