Three Australian employees of billionaire James Packer's Crown Resorts have been formally arrested in China, Foreign Minister Julie Bishop said Wednesday, as Beijing cracks down on high-roller gambling promotions.

Eighteen Crown staff, including the three Australians, were held in raids in October on suspicion they were organising gambling activities overseas for Chinese nationals.

Gaming companies are not allowed  explicitly to advertise gambling in China.

"We have been formally advised that three Australians have been arrested on suspicion of gambling-related offences," Bishop told Sky News.

She said consular officers visited the trio on Tuesday and they were in good health and being represented by lawyers.

"There is... an overall anti-corruption agenda of (Chinese) President Xi Jinping and gambling is one of the areas of interest to them," she added.

"We are subject to the laws of China, we are subject to the laws of the country that we are visiting or we are operating in."

One of those being held is Jason O'Connor, the executive vice president of a Crown division called VIP International.

There was no immediate comment from Crown.

Packer last month said he was "deeply concerned" for the detained employees.

Crown operates casinos across Australia and the world, including in Macau, where revenues have been hit hard by a Chinese corruption crackdown that has driven away many big-spenders.

Graft is endemic in China and Xi launched a much-publicised anti-corruption drive after he came to power in 2012.