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.

Chinese law enforcement authorities have restricted Mao’s exit in accordance with the law, Guo Jiakun, a spokesperson for the ministry, told a regular press briefing.

The U.S. bank had suspended all travel to China after Mao’s exit ban, a person familiar with the matter told Reuters last week.

The case was being investigated and Mao was obliged to cooperate with the investigation, Guo said, without elaborating on the case or how the banker was involved.

“Everyone in China, whether they are Chinese or foreigners, must abide by Chinese laws,” Guo said, adding that China will protect their legitimate rights and interests in investigations.

Mao, who was born in Shanghai and based in Atlanta, currently serves as a managing director at Wells Fargo, specialising in the international factoring business.