Ousted former Kedah menteri besar Mukhriz Mahathir wants the Conference of Rulers to summon the various agencies probing 1MDB, and to brief them on their investigations.

"I plead to your majesties to summon the attorney-general, Bank Negara Malaysia governor, inspector-general of police, Malaysian Anti-Corruption Commission (MACC) chief, auditor-general, and Public Accounts Committee (PAC).

"(Summon them) to report truthfully to the Conference of Rulers on their 1MDB investigations, without protecting any parties," Mukhriz said in a statement today.

He added if the rulers are unable to call on the investigators due to "interference from those being investigated", or if their reports are untrustworthy, then a Royal Commission of Inquiry on 1MDB should be set up.

"This is to uncover the truth on 1MDB as soon as possible," Mukhriz said.

Last October, the Conference of Rulers had urged the 1MDB investigators to hasten their probe and for those who have committed wrongs to be punished.

Mukhriz, however, said Prime Minister Najib Abdul Razak has given little heed to this royal decree, acting instead as 1MDB's spokesperson and defending it against attacks.

The 1MDB scandal went beyond its debts last year when a former subsidiary, SRC International, was revealed by the Wall Street Journal to have banked in RM42 million into Najib's personal accounts.

Najib has since denied any wrongdoing, and attorney-general Mohamed Apandi Ali has confirmed that the premier had not committed any criminal offence.

This is Mukhriz's first statement since resigning as Kedah menteri besar on Thursday.

The son of former premier Dr Mahathir Mohamad had said he would use his "freedom" to speak more openly against the wrongs of the Najib administration.