China's foreign ministry said on Monday that Chenyue Mao, the Wells Fargo banker who has been blocked from leaving the country, was involved in a criminal case and obliged to cooperate with the investigation.

China is preventing a Chinese American banker for Wells Fargo and, separately, an employee of the U.S. Patent and Trademark Office from leaving the country.

Chinese authorities have placed an exit ban on a China-born executive after she entered the country recently. The bank has suspended travel to China.