William Yan gambled $NZ300 million in the casino's VIP lounge between 2001 and 2013. The combined total of money gambled and won by the businessman over the period was $NZ563 million, reports the NZ Herald.

The New Zealand citizen is now at the centre of a money-laundering investigation and, following the 2014 raid of his $NZ2.5 million Auckland apartment, has had $NZ40 million worth of assets seized by the authorities.

New Zealand police are working closely with Chinese police, who claim Mr Yan stole the money while working as chairman of a pharmaceutical company in 2000.

The ongoing inquiry focuses on Mr Yan's gambling habit and a string of expensive purchases including homes, cars and stakes in companies.

In one instance, $NZ2.3 million was transferred via a foreign exchange dealer to Mr Yan's wife who then deposited the bank cheques into SkyCity accounts. Thirty minutes later, $NZ500,000 worth of cash and chips was withdrawn and handed to an estate agent inside the casino for the cash purchase of an apartment on the 35th floor of the nearby Metropolis complex.

Mr Yan was granted New Zealand citizenship after moving to the country in 2001 despite having at least three other identities and an Interpol alert against his name, reports the newspaper.

Mr Yan's lawyer, David Jones, QC, declined to comment on his client's gambling. No criminal charges have been laid against Mr Yan, who denies any wrongdoing.

New Zealand's Department of Internal Affairs has described Mr Yan as "one of a number of gamblers of significance whom the department has discussed in its interaction with SkyCity".

Authorities consider Mr Yan's gambling habit an "indication of wealth".

A SkyCity spokesperson said that "the level of play will vary tremendously depending on the financial circumstances of a customer, and it is not necessarily unusual for a wealthy VIP player to generate significant turnover."

A trial date is yet to be set and investigations continue.