Multiple media outlets reported earlier Friday that the employee involved was Chenyue Mao, an Atlanta-based managing director who was born in Shanghai.

Mao had entered the country in recent weeks but is now unable to leave, they said.

"We are closely tracking this situation and working through the appropriate channels so our employee can return to the United States as soon as possible," the company told AFP when asked to confirm the reports.

The company declined to give further details.

The San Francisco-based bank is now restricting its employees from visiting China following this case, reports said.

Beijing's foreign ministry spokesman Lin Jian said he was "not familiar" with the specific case when asked about it at a news conference on Friday.

"China is a country governed by the rule of law. Whether a person is Chinese or foreign, in China both must respect China's laws," Lin added.

Global firms have faced an increasingly difficult business environment in China in recent years, industry groups say, citing a lack of transparency on data laws and prolonged detentions of employees in the country.

A court in China sentenced a Japanese businessman from pharmaceutical company Astellas to three-and-a-half years in prison on Wednesday for spying.

Pharmaceutical giant AstraZeneca in November said that the head of its China operations Leon Wang had been detained, after reports the firm was under investigation for potentially illegal data collection and drug imports.

And in 2023 a senior executive at US risk advisory firm Kroll was prohibited from leaving China, the Wall Street Journal reported.