BEIJING — Chinese police have launched an investigation into 22,800 cases of tax-related crimes involving more than 560 billion yuan ($81.3 billion) since 2018, the Ministry of Public Security said on July 31.

About 90 percent of the cases involved offenses of falsely issuing exclusive value-added tax invoices, said You Xiaowen with the ministry at a press conference.

Other crimes include defrauding export tax refunds, which posed great difficulties for police investigation as well-concealed methods had been used in such illicit activities, said You.