President Donald Trump's bid to open Sydney's first casino 30 years ago was thwarted after regulators expressed concern over his alleged "mafia connections", it was revealed on Wednesday.

Australia's New South Wales (NSW) police board recommended against approving an offer from the former New York businessman and a local developer, according to a report from The Australian, because it would have been "dangerous".

The now U.S. president, in partnership with the Queensland-based Kern Corporation, was one of four groups bidding for the lucrative Darling Harbour project in Sydney. However, the NSW government rejected the pair's proposal on 5 May 1987, along with two other bidders.

At the time Trump owned two casinos in Atlantic City – Trump Plaza and Trump's Castle – and was poised to open a third with the Trump Taj Mahal.