MACC chief commissioner Azam Baki did not disclose the length of the extension given but said Mirzan and Mokhzani’s lawyers have been informed of the matter, Bernama reported.

“We have set the (specific) ‘time of interest’ for the asset declaration. We have reached an agreement on the matter,” he told reporters after an event at the World Trade Centre Kuala Lumpur today.

Last month, Mirzan and Mokhzani urged MACC to specify the “time of interest” of its investigation into their father, saying that some old documents sought “are no longer in existence”.

The siblings were ordered by MACC in January to declare their assets dating back to 1981, the year Mahathir became prime minister.

The brothers have received two extensions of the original February deadlines for compliance.

They have denied claims that they required a longer time to comply with the order because of their “excessive wealth”.

Azam previously confirmed that Mahathir was under investigation, after the two brothers were reported by Bloomberg as saying that their father was the agency’s “primary suspect” in its probe.

On May 23, Mahathir said he was willing to declare his assets if requested, but MACC had yet to order him to do so.