Crown Resorts says all of its employees detained in China, including several Australians, have been charged with gambling promotion offences.

Key points: Three Australians, including two dual citizens, are among those in detention

Three Australians, including two dual citizens, are among those in detention They were arrested last October during raids in four cities

They were arrested last October during raids in four cities The charges relate to the promotion of gambling, which is illegal in China

Three Australians and more than a dozen Chinese staff from Crown were arrested after police raids across four cities in China last October.

There are a total of 19 people charged with gambling offences and they will face Baoshan District Court on June 26.

It is believed 14 people, including the three Australians, are still being held by authorities. One has been released on bail.

Gambling, and its promotion, is illegal in mainland China.

The Australians, being detained in Shanghai, are members of Crown's sales and marketing team.

They include Jason O'Connor, the Melbourne-based head of Crown's International VIP programs, who was arrested en route to Shanghai airport.

Also detained were dual Australian-Chinese nationals Jerry Xuan and Jenny Pan.

A DFAT spokeswoman said the Australian Government was providing consular assistance to three Australians detained.

Ms Jiang has since been released from custody, her husband said. ( Supplied: Jeff Sikkema )

Crown's vice-president in China, Malaysian citizen Alfread Gomez, 50, and Chinese staff Jenny Jiang and David Dai Bin were also among those taken into custody.

Jiang has since been released from detention.

A spokesman from the Malaysian consulate in Shanghai said it had been providing Gomez "consular support from time to time" but that he had his own lawyer.

Gomez, who is being detained in Shanghai, is said to have been working in the city at the time he was arrested, but it is not clear if he was based in there or just visiting.

Senior Crown employee Jason O'Connor, from Melbourne, is among those detained in Shanghai. ( Supplied )

If convicted, the Crown workers could face up to 10 years' prison.

"Crown Resorts Limited announced today that all its detained employees in China, as well as those employees released on bail, have now been charged with offences related to the promotion of gambling," Crown said in a statement, released to the Australian Stock Exchange today.

"Their cases have been referred to the Baoshan District Court."

The staff have been listed for trial on June 26.

University of Western Australia Professor Nolan Sharkey, a barrister who has consulted for Australian and Chinese organisations and governments, said the time taken to charge the staffers was "unusual for things in China".

"In this case, they could be more concerned about wanting to present that they are doing the right thing," Professor Sharkey said.

"I suppose they are taking their time to counter accusations that they are acting arbitrarily and are dealing with it properly under Chinese law."

The Crown group holds casino licences in Melbourne, Perth and Sydney, where its Barangaroo property is scheduled to open in 2021.

In March, the ABC's Four Corners reported Crown had developed a business model based on luring rich Chinese, known as VIP high rollers, to its casinos.

Since the arrests of its staff, Crown Resorts announced it would sell off its major stake in its business in Macau, where it operates several casinos.

The former head of the NSW casino regulator, Chris Sidoti, also warned in March that Crown's Australian casino licences could be reviewed if any of its staff under arrest in China were convicted.

Crown said it would make no further comment.