Former premier Dr Mahathir Mohamad has admitted that Prime Minister Najib Abdul Razak is right that he was wrong about 1MDB's RM42 billion debt.

"The (Public Accounts Committee) report says it's not just RM42 billion but RM50 billion. More than that.

"So I was wrong on that because I named a smaller figure and I think the RM50 billion is also not correct, there could be more," Mahathir told reporters in Kuala Lumpur today.

He also demanded to see where the money was.

"Show me where it is. It is here and there but we don't see."

Najib earlier today said the PAC report on 1MDB proved Mahathir's allegations that RM42 billion was missing from the fund was wrong.

The report, however, stated that 1MDB's debts had grown from RM42 billion in March 2014 to RM50 billion as of January 2016.

Mahathir has been citing 1MDB's debts as one of the reasons the prime minister should step down from office.

The former premier is currently spearheading a campaign to collect public signatures in a bid to pressure Najib to quit.