If the ex-cabinet trio who raised concerns about 1MDB are gentlemen, they should have voiced up while still in government, Dewan Rakyat speaker Pandikar Amin Mulia said today.

"If they are gentlemen, why didn't they say 'I don't agree' while they were in cabinet?" Pandikar asked at a press conference in the Parliament reception room.

He was commenting on the probe against former ministers Husni Hanadzlah, Muhyiddin Yassin and Shafie Apdal, who have been accused of breaking their ministerial oaths of secrecy when commenting on 1MDB while debating on Budget 2017.

Opposition lawmakers have cried foul at the probe, saying the three should be protected by parliamentary immunity.

However, Pandikar said he did not have the authority to order the police to halt the investigation, as some have asked him to.

He also said that it was not up to him to decide whether parliamentary immunity extended to the Official Secrets Act (OSA).

"Let the court decide... It is not my responsibility to interpret the constitution or statutes. I interpret the (House) Standing Orders," he said.

Be mindful of the law

Pandikar also clarified that he did not know if the trio's speeches breached government secrecy rules.

He said his remarks at a press conference last week were merely a reminder for them and other lawmakers to be mindful of the law.

Citing British parliamentary conventions, the speaker said there was an unwritten rule about ministerial responsibility, which was upheld even when the ministers have either quit or retired.

He said writings about government matters were even held to be secrets after the writer's death.

He cited the case of Richard Crossman, whose posthumously discovered diaries were the subject of a legal battle because the British government tried to prevent it from being published.

This case he said, would likely be referred to if the trio were tried in court.