Casino operator Las Vegas Sands’ policy of allowing Chinese gamblers to use their UnionPay bank cards to purchase casino chips at its Singapore resort Marina Bay Sands reportedly has Beijing bankers plotting revenge.

Earlier this month, the South China Morning Post reported that Marina Bay Sands was running a ‘resort entertainment’ voucher program that allowed China UnionPay cardholders to purchase gambling chips, in apparent violation of card policy.

Informed of Sands’ chip purchasing program, Xie Zhong, payment settlement director of the People’s Bank of China, told the SCMP that UnionPay cards “should certainly not be used in casinos.” The Singapore Casino Regulatory Authority declined multiple requests for comment on Sands’ policy.

Las Vegas Sands’ corporate spokesman Ron Reese defended its policy, saying the voucher program “was designed to give guests flexibility in purchasing a variety of goods and services.” Reese further claimed that the voucher program operates “in accordance with the terms and conditions of China UnionPay cards.”