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.