The country’s Securities Commission meanwhile said it was looking into the allegations, which centre around claims that Azam had bought millions of shares in two public companies between 2015 and 2016, contravening rules on such shareholding by civil servants.

He has said his brother had used his trading account to purchase the shares.

On Saturday, the prime minister said it was wrong to interpret his silence as inaction.

“Let’s wait for the investigation to be completed. We cannot jump to the conclusion that Azam Baki is guilty. We have to be fair to all and only take action after the investigation is completed,” Ismail Sabri was quoted as saying by the national news agency Bernama.

‘Like Najib’s 1MDB playbook’: Malaysian graft-buster ridiculed in stock saga

The MACC’s three deputy commissioners meanwhile issued a joint statement backing Azam, 58.

“On behalf of all of MACC’s staff, we state our stand to support the leadership of MACC chief commissioner Azam Baki,” Ahmad Khusairi Yahaya, Norazlan Mohd Razali and Junipah Wandi said in the statement.

“We believe that the slander and attacks are motivated by political revenge to bring down the image and credibility of MACC.”

Their statement in turn triggered a sharp response from opposition figures.

Lim Guan Eng, leader of the Democratic Action Party (DAP) and a former finance minister, said Ismail Sabri was risking his personal standing – already hit hard by the government’s mismanagement of recent floods – by allowing the controversy at the MACC to fester.

There have been widening calls for Azam to step aside while the Securities Commission probe is under way, and Lim said it was “ethically, morally and even legally untenable” for the MACC chief to remain in charge of the agency during the investigation.

Gobind Singh Deo, another senior DAP figure, said on Monday it was critical for the MACC to show that action would be taken against any individual – including senior officers – if they were found to have acted against the law.

Said Gobind: “The MACC may be called in to assist the police investigation in this case. How can the community be confident about the assistance that will be rendered when the MACC in the first instance has voiced support for a party involved in the probe?”

Who wins and loses after Najib’s conviction in Malaysia?

Government critics have also taken aim at Azam for sending a letter of demand to local anti-graft whistle-blower Lalitha Kunaratnam over her reports on the saga on the Independent News Service website.

That move drew particular derision, with online commenters pointing to Azam’s recent voicing of support for additional legal protection for whistle-blowers.

Azam, already ridiculed last week for suggesting his brother had accessed his trading account to purchase shares – an act that is illegal under Malaysian law – remained the primary focus of the country’s political satirists.

Local cartoonist Zunar drew a cartoon depicting a wordplay of the badge “I am against corruption” – Saya Anti Rasuah – worn by police and other government servants, changing it to – Saya Nanti Rasuah – “I welcome corruption”.

Similarly, political satirist Fahmi Reza published a Spotify playlist of 50 songs themed around brotherly love, calling it “My Dear Little Brother” with a caricature of Azam Baki on the cover.

The MACC, which sits under the prime minister’s office, has sweeping powers to investigate graft in the country but has long had a reputational problem.

Some of its officers have also been involved in cases of abuse of power and impropriety.