Three Australians went on trial in China on Monday along with a...

Three Australians went on trial in China on Monday along with a dozen other Crown Resorts Ltd (CWN) employees and former employees accused of gambling crimes, following a lengthy probe into how the firm lured Chinese high-rollers to its casinos.

The 19 defendants were formally charged earlier this month, having been first detained late last year, and the trial at Baoshan District Court in the north of Shanghai is expected to reach a fairly swift conclusion.

Melbourne-based Crown is 49 percent owned by billionaire James Packer, and the most senior employee on trial is its Australia-based head of international VIP gambling Jason O'Connor.

Three of the accused, believed to have been junior staff, had been released on bail.

Family members were ushered into the courthouse as they arrived with lawyers in a convoy of cars on Monday morning, and some wore masks. Journalists were barred from attending proceedings.

The case has forced Crown to tear up its strategy of luring wealthy Chinese to the casino hub in the Chinese territory of Macau and instead shift its focus back home.

Crown does not directly run casinos in China. But it relies heavily on Chinese gamblers at its Australian operations, as it had done in Macau until last month when it sold its remaining stake in Macau-focused Melco Resorts & Entertainment Ltd for $1.16 billion.

China has been cracking down on attempts by casinos to woo high-spending Chinese gamblers within China. In 2015 thirteen South Korean casino managers were arrested in China for offering Chinese gamblers free tours, free hotels and sexual services.

The trial is the latest in a series of high-profile cases in China involving foreign firms. British drugmaker GlaxoSmithKline PLC was fined nearly $500 million in 2014 and food maker OSI saw employees jailed last year. ($1 = 6.8390 Chinese yuan renminbi)