An Atlanta-based banker working for Wells Fargo has been prevented from leaving China, the latest incident that threatens to amplify concerns among Western executives about the potential consequences of visiting the world’s second-biggest economy.

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.

SINGAPORE—China blocked Wells Fargo banker Chenyue Mao from leaving the country because she is required to assist in a criminal probe, China’s Foreign Ministry said Monday, marking Beijing’s first confirmation of the exit ban.