According to a Hong Kong court writ, Kong, who won gold at the 1996 and 2000 Summer Games, faces a HK$2.55 million ($327,000) lawsuit over a debt to a luxury hotel in Singapore.
The writ submitted to the court by the Marina Bay Sands hotel said Kong signed a credit agreement two years ago to borrow S$1 million from it. The writ said Kong had since repaid S$545,625, but failed to offset the balance in full, leaving S$454,375 unpaid.
Kong said he had borrowed money for his family and friends while on holidays in Singapore but had not gambled it himself, according a post on his Weibo account, China's equivalent of Twitter.
China has a "zero-tolerance attitude" towards behaviour which violated sporting ethics and laws, China's General Administration of Sport, the country's government agency which oversees sport, said in a statement on its website.
Kong was ordered to return to China from the table tennis world championships, which are currently underway in Germany, to help with the investigation, China's official Xinhua news agency said on Tuesday.
($1 = 1.3869 Singapore dollars)
(Reporting by Sue-Lin Wong; Editing by Peter Rutherford)
