Chinese police have visited the Shanghai office of American management consulting firm Bain & Company and questioned employees there, according to a company spokeswoman on Wednesday.

“We are cooperating as appropriate with the Chinese authorities,” the spokeswoman told Reuters via email. “At this time, we are unable to comment further.”

The U.S. embassy in China and the American Chamber of Commerce in Shanghai did not immediately respond to requests for comment.

The Financial Times, citing people briefed on the surprise visit two weeks ago, first reported on Wednesday that the police took away computers and phones but did not detain any employees.

The police made more than one visit to Bain in Shanghai, FT said, noting that the purpose was not immediately clear and whether the raids were connected to the firm or its clients.

American companies worry that China may be stepping up retaliatory action because of measures taken against Chinese firms by U.S. President Joe Biden’s administration.

Chinese authorities last month raided the office of U.S. corporate due diligence firm Mintz Group in Beijing and detained five local staff.

U.S. businesses operating in China are increasingly pessimistic about their prospects in the world’s second-largest economy, according to a survey released this month by the American Chamber of Commerce in China.

China has said it welcomes foreign trade and investment but stressed that security comes before development.

Over two years, Beijing has clamped down on antitrust violations, banned private tuition groups and reined in a debt binge by property developers, wiping hundreds of billions off the market capitalisations of some of its largest companies, including e-commerce giant Alibaba and social media giant Tencent.