SYDNEY, Oct 18 (Reuters) - Billionaire James Packer, the...

SYDNEY, Oct 18 (Reuters) - Billionaire James Packer, the majority owner of Australian Crown Resorts Ltd (CWN), said on Tuesday he was very concerned for 18 company employees detained in China for suspected "gambling crimes."

Three Australians are in the group detained late last week, including Crown's head of international VIP gambling Jason O'Connor, in what the industry fears could be a crackdown by Beijing on the promotion of offshore gaming by international companies.

"I am deeply concerned for the welfare of those Crown employees detained in China," Packer, who owns 53 percent of the Australian-listed company, said in a statement.

"I am respectful that these detentions have occurred in another country and are therefore subject to their sovereign rules and investigative processes."

China's Foreign Ministry told Reuters in a statement on Monday that the group were being held for suspected "gambling crimes," and that it was still investigating.

Casinos cannot advertise in China and promoting gambling in other ways, such as advertising resort facilities or offering credit to high-spending clients, can also be problematic.

Thirteen South Korean casino managers were arrested in China last year for offering Chinese gamblers free tours, free hotels and sexual services.

Crown shares suffered their largest ever one-day decline on Monday, falling by 14 percent, while smaller Australian rival Star Entertainment Group Ltd (SGR) dropped as much as 6 percent, amid concerns about the impact the detentions would have on the companies' ability to attract wealthy Chinese gamblers to major new developments in Australia.

Prime Minister Malcolm Turnbull, whose government has been criticised by Beijing for blocking proposed takeovers of Australian utilities and agriculture holdings, said on Tuesday he was concerned about the arrests, but spoke in general terms.

"When Australians get into trouble overseas, we always provide consular support and that is precisely what is happening there now," Turnbull said on Australian Broadcasting Corporation radio.

Australia consular officials in Shanghai were making arrangements to visit the detained Australians, the Australian Department of Foreign Affairs and Trade said in a statement late on Monday, without specifying when the meetings would take place.

Packer said Crown was awaiting further details from the Chinese authorities.