The extent of wrongdoing in 1MDB is far greater than what is publicly known, revealed Dr Mahathir Mohamad today.

The prime minister drew the conclusion after being briefed by police and auditor-general Madinah Mohamad over the scandal involving the state investment firm.

"It was clear that the wrongdoing is more than what was known by the public, and by me.

"We will take action to lodge a police report. When there is an opportunity we will make the arrest, we will get the person involved in the wrongdoing," he added.

Meanwhile, Mahathir said the government will write to US, Singapore and Switzerland to repatriate allegedly misappropriated 1MDB-linked funds, and use that money to service various debts.

"We will recover this money from US, Switzerland and Singapore, probably Luxembourg also. We will contact them to recover the money.

"There was no admission from the administration of Najib Abdul Razak that the money came from 1MDB and was laundered in the US, therefore there was no application to claim the funds.

"But, we want to state that the money was from 1MDB and Malaysia, and we will apply to recover the funds," he added.

Mahathir noted he was unclear of the amount of funds linked to the investment firm still overseas, but he knew there was US$4.5 billion in US.

He added that it is up to the police whether to summon Najib to record a statement over the scandal, but dismissed a question on whether the former prime minister is currently under house arrest.

Mahathir also stressed that his administration has to honour the government-guaranteed debt incurred in 1MDB, or risk being sued and ending up bankrupt. 

He admitted, however, he was in the dark the total amount of debt incurred by the investment firm.

"I have no way to determine the amount and all that, I don't have full information on this. I had to rely on official reports," he said when asked about an expert who claimed that this amount could reach RM70 billion, based on the auditor-general's 1MDB report.