The Malaysian authorities have frozen six bank accounts believed to be linked to a money trail allegedly involving nearly US$700 million (S$943 million) moved from debt- laden 1Malaysia Development Berhad (1MDB) into Prime Minister Najib Razak's personal accounts.
Documents related to 17 accounts from two banks were also seized yesterday to aid investigations.
This comes as calls grow louder for the embattled leader to confirm or deny the allegations, first made by The Wall Street Journal (WSJ) last Friday. Datuk Seri Najib has said only that he never used public funds for "personal gain".
The WSJ backed up its claims yesterday by releasing redacted bank documents and flow charts that purportedly show how the money was channelled into Mr Najib's AmPrivate Banking accounts.
A special task force comprising the police, Attorney-General's Office, Bank Negara and Malaysian Anti-Corruption Commission is leading the investigation.
"An order to freeze six bank accounts of the parties suspected to be involved with the case was issued on July 6, 2015," it said in a joint statement, without identifying the holders of the accounts.
The Malaysian Insider news portal, citing sources, said three of the frozen accounts belong to Mr Najib and that two banks are AmBank and government-linked Affin Bank.
Yesterday's joint statement also said documents concerning non- compliance with central bank regulations were seized from the banks.
Three companies raided last Saturday after they were named in the WSJ report are SRC International, an energy firm owned by the Finance Ministry; SRC subsidiary Gandingan Mentari; and Ihsan Perdana, which carries out corporate responsibility projects for 1MDB.
Mr Najib has rubbished the idea that he would use a local bank account - AmBank is Malaysia's fifth largest bank - to steal the money and said he would never betray Malaysians by using state funds for "personal gain".
Analysts say a criminal charge against a sitting prime minister would be unprecedented.
Former premier Mahathir Mohamad slammed Mr Najib and 1MDB for "shaming the country" on his blog yesterday. "In other countries, a leader involved in a scandal like this would have resigned and apologised. Before this, the country was never subjected to ridicule with unanswered allegations like now," said Tun Dr Mahathir, who has led calls for Mr Najib to resign.
Opposition and civil society leaders yesterday urged Mr Najib to take leave of absence to allow the probe to proceed without interference. They also called for fresh polls since the funds were allegedly used to help the ruling Barisan Nasional win the 2013 election.