(Bloomberg) -- Macau’s gaming watchdog has restricted the use of artificial intelligence tools that may help casino operators track gamblers likely to bet big, according to people familiar with the matter.

The Gaming Inspection and Coordination Bureau has asked casinos in Macau not to install any digital surveillance equipment including cameras or facial recognition system that the regulator hasn’t approved, according to people who have seen the July 30 directive but asked not to be named as the document is confidential. The new rules kicked in from Aug. 1, these people said.

The regulator did not immediately respond to a request for comment.

The latest clampdown on casino owners in Macau, the Chinese territory that’s the world’s biggest gambling hub, follows a Bloomberg report in June that showed how operators there were starting to use hidden cameras, face recognition technologies, digitally-enabled poker chips and baccarat tables to track gamblers. These provided data that helped the companies spot who among their millions of customers are likely to lose the most money.

The regulator has also directed companies to comply with laws pertaining to personal data. Any video or data used or obtained from these high-surveillance tools is to be kept only by the casino operators, according to these newly issued rules.

The Bloomberg Intelligence gauge of Macau casino operators, which includes MGM China Holdings Ltd., Sands China Ltd. and Wynn Macau Ltd., slipped almost 10% last week amid a broader market sell-off and an unexpected drop in July’s gaming revenue, marking its worst weekly fall since November last year.

The new algorithm-driven technology processes the way gamblers behave at the betting table and maps them according to their risk appetite. The higher the appetite for risk, the more likely it is for the customer to lose and the more profit a casino tends to make, sometimes up to 10 times more.

(Updates with regulator response in third paragraph)

To contact the reporter on this story: Jinshan Hong in Hong Kong at jhong214@bloomberg.net

To contact the editors responsible for this story: Rachel Chang at wchang98@bloomberg.net, Bhuma Shrivastava, Jeff Sutherland

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