Perth Mint’s international reputation has been damaged by gold “doping” revelations and past anti-money laundering failures, its chief executive admits.

The West Australian government-owned corporation has admitted it diluted gold it sold to China with the addition of silver to save money, at least once, between 2018 and 2021.

An investigation by the ABC’s Four Corners program found the Shanghai Gold Exchange had raised complaints about two gold bars that did not meet its strict specifications.

An internal report into the incident raised concerns “up to 100 tonnes of stock” worth billions of dollars could be recalled to Perth to be recast at taxpayers’ expense.

Mr Waters, who arrived at Perth Mint after the doping incident in April last year, on Tuesday said all gold sold during that period had exceeded the minimum 99.99 per cent industry standard.

But he said it was “unacceptable” the mint had breached the tougher Shanghai specifications and exposed itself to reputational harm.

“It’s a serious issue. It shouldn’t have happened,” he told reporters.

“These sorts of issues are bad for our reputation … I want to see that repaired and get us back to the reputation that we should have.”

Mr Waters said he had discussed the topic with Mines Minister Bill Johnston upon taking office but declined to comment on when the government had become aware of the practice or the size of the potential taxpayer liability.

Mr Johnston is in Asia for a trade mission and Premier Mark McGowan is yet to comment on the Perth Mint revelations.

Senior government minister Rita Saffioti on Tuesday said she was unable to answer questions on the topic but expected the premier would in coming days.

Perth Mint remains under investigation by financial crime regulator AUSTRAC, which last year ordered the appointment of an external auditor to examine concerns about its compliance with anti-money laundering and counter-terrorism financing obligations.

Mr Waters said those concerns were “historical” but conceded the mint still needed to improve its systems and transparency.

“This report from AUSTRAC will be handed down this year … we’ll be held to account for it and we’re going to get better,” he said.

Four Corners reported former Hells Angels bikie Dayne Brajkovich had purchased $27,000 in gold from the mint in June last year.

The mint is required to conduct extensive checks on higher-risk customers but Mr Brajkovich told the program he was only asked for his driver’s licence.

There is no suggestion Mr Brajkovich’s money was sourced from illegal activity.

Perth Mint is Australia’s biggest gold refinery with a turnover of almost $22 billion last financial year.

-AAP