BEIJING — Authorities in China have released all employees of an American corporate due diligence firm detained in Beijing around two years ago.

The release of the employees from the firm, the Mintz Group, comes as China is trying to woo back foreign investors to help revive its sagging economy.

“We are grateful to the Chinese authorities that our former colleagues can now be home with their families,” the Mintz Group said in a statement to NPR.

Like other due diligence firms, the Mintz Group does investigations and audits to assess risks for its clients. According to its website, the company currently has 12 offices around the world.

Chinese authorities raided several firms’ offices, including Mintz’s, in spring 2023, just as Beijing was preparing to host top executives at American multinationals for an annual economic conference.

Mintz was later fined for conducting unauthorized statistical investigations. It is not clear what statistics were involved. The firm has now closed its Beijing and Hong Kong operations.

China has stepped up its scrutiny on foreign research firms in recent years. It has also beefed up regulations that more strictly control corporate and trade data flows.

Earlier in 2021, Chinese police raided a foreign auditing firm working on investigations related to China’s western Xinjiang region, where the United Nations says China may have committed crimes against humanity.

Later, authorities raided and questioned employees at a large marketing research office in Shanghai.

The release of the Mintz employees comes a day after an economic forum in Beijing, where Chinese officials promised better market access for foreign investors.