The Federal Government has been formally notified of the arrest of three Australian Crown employees who were detained last month on suspicion of violating strict Chinese gambling regulations.

After more than five weeks behind bars, the three employees of Crown Resorts Ltd were formally arrested on Friday (local time) “on suspicion of gambling”, Chinese Foreign Ministry spokesman Geng Shuang said at a briefing.

Mr Geng did not offer details on the allegations they faced.

Foreign Minister Julie Bishop confirmed the arrests in a statement to the ABC, adding the three Australians remained in detention in Shanghai and had been visited by Australian consular officials.

Julie Bishop describes the arrests as “a very difficult circumstance”. Photo: file

She said the three Australians were “in good health”.

“They are all represented by lawyers and we were able to provide advice and support and messages from their families,” Ms Bishop told Sky News.

“It is a very difficult circumstance, but we will continue to provide whatever advice and support that we are able.”

In Chinese law, formal arrests keep people behind bars so that police and prosecutors can spend up to six months investigating and preparing charges.

Casino gambling is illegal in mainland China and agents are banned from organising groups of more than 10 Chinese citizens to gamble abroad.

According to Chinese law, anyone who “runs a gambling house or makes gambling his profession” can face up to three years in prison.

The industry has been known to skirt the ban by touting destination packages rather than gambling, particularly as Chinese President Xi Jinping’s ongoing corruption crackdown has deterred some gamblers from the Chinese gambling enclave of Macau.

Status of other detained Crown employees unknown

The three Australians include the head of Crown’s VIP International team, Jason O’Connor, who was visiting China from the company headquarters in Melbourne when he and others were detained in October.

He is responsible for attracting wealthy high rollers to Crown’s casinos in Australia.

It is understood that the other two Australians live in China.

Fifteen Chinese employees of Crown were also detained, and the status of their cases is not known.

James Packer is concerned over developments. Photo: AP

In October, billionaire casino magnate James Packer expressed “deep concern” for the detained Crown Casino employees.

No details have been released from defence lawyers, Crown or China’s public security ministry, but it is believed Crown’s efforts to lure high rollers to gamble in Melbourne is at the core of the case.

In its last profit update, Crown cited a rise in foreign visitors to Australia — particularly those from China — as a highlight, given that the Macau operation is hurting from the Chinese corruption crackdown.

Melco Crown’s Altira Macau. Photo: Crown Resorts

Crown’s three Chinese casinos are on the island of Macau.

The fallout could hurt Crown’s operations in Melbourne and Perth along with James Packer’s new project at Barangaroo in Sydney, which will have no poker machines and have a heavy reliance on high rollers, including ones from China.

Analysts have said such arrests are not unprecedented for foreign casino operators in China, and foreigners are usually dealt with on a case-by-case basis.