Pressure is mounting on the ANZ bank board after New Zealand’s central bank ordered two independent reviews into the company’s conduct following the departure of its NZ chief executive who ran up expense accounts averaging more than $400,000 a year.

The bank’s chairman, former New Zealand prime minister Sir John Key, last week announced the departure of David Hisco, who is an Australian, after the company learned of his spending for “non-monetary benefits” including a personal chauffeur service and wine cellaring.

He told reporters that Hisco, who had been chief executive for the past eight years, had a “blind spot” when it came to tagging personal expenses as business ones. This included spending $50,000 on a personal chauffeur service as well as the company paying to store his wine collection in Australia.

However, since then, more blurring of the lines between personal and business affairs has emerged – including that Hisco last year bought Key’s $3.5m beach house north of Auckland. Then it was revealed that in 2017 Hisco’s wife also bought the couple’s Auckland family home from ANZ for substantially less than its capital valuation.

Deborah Walsh paid $6.9m in July of that year for the property in the affluent Auckland suburb of St Heliers. This was less than the $7.55m ANZ paid when it bought the house in early 2011. Its capital value in 2017 was $10.75m.

Hisco, 55, was paid $3.12m a year, however, and averaged more than $440,000 a year in expenses on top of that.

He stepped down several weeks ago, a move the board said at the time was due to health reasons as well as “board concern about the characterisation of certain transactions following an internal review of personal expenses”.

He exited with a year’s salary but gave up $6.4m in company equity.

Hisco’s replacement, Antonia Watson, said it was a “day of shock and disappointment”. She said [Hisco] was well liked as a leader but that “[he] has not met the standards and expectations”.

Hisco’s departure comes at a trying time for the bank. Despite recording record profits of $2bn last year, ANZ was recently censured by the reserve bank for incorrectly attesting to risk compliance over five years. The reserve bank requires banks to maintain a minimum amount of operational risk capital, which is determined relative to the risk of each bank’s business.

The Reserve Bank of New Zealand on Monday also asked for two reports from the bank to provide assurance it was operating in a prudent manner.

Key said in a statement the bank had already been working on commencing an independent review.

Sam Stubbs, the managing director of Simplicity, which provides fund management for New Zealand’s national saving scheme, said an independent inquiry into the Hisco issue was also required.

“This needs a proper, government-funded royal commission of inquiry,” he told Newshub.

“The reason for this is most KiwiSavers own shares in ANZ, or most of them are invested in ANZ – this is the country’s biggest bank, and most profitable company.

“What they do really, really matters.”