The Chinese government has freed three activists who were detained while investigating working conditions at a company that made shoes for the Ivanka Trump brand, according to an advocacy group.

The men were released on bail and are awaiting trial, according to China Labor Watch, the organization they were working for.

It's not clear what the men are charged with. Local police in Jiangxi province declined to comment on the case Thursday. The Chinese government has previously said the men were put under criminal detention because of their use of "illegal monitoring devices."

Su Heng, Li Zhao and Hua Haifeng worked undercover at two factories before they were detained in late May, according to China Labor Watch.

The organization says the factories made shoes for the Ivanka Trump brand, along with Marc Fisher, Kylie + Kendall, Coach and other brands.

Kylie + Kendall said in a statement it does not comment on its procedures but all factories it works with "are required to operate within strict social compliance regulations."

Marc Fisher and Coach did not immediately respond to a request for comment.

The Ivanka Trump Company has told CNNMoney that its products have not been produced at the factory in question since March. It has said that the factories it uses "are required to operate within strict social compliance regulations."

China Labor Watch said it hopes the Chinese courts "will provide the investigators with a fair trial." It said the men's lawyers do not believe the men committed crimes.

The U.S. State Department, which had called for China to release the men, had no immediate comment. The Ivanka Trump said it had no comment.

Related: China won't release activists detained in probe of Ivanka Trump supplier

The activists took jobs in March, April and May at factories run by Huajian Group, a Chinese shoe manufacturer.

The advocacy group says it has documentation of worker abuse, and says it sent letters to Ivanka Trump and her brand, as well as several other companies that have used the factories. No one has responded to those letters, according to China Labor Watch.

Huajian Group has denied the allegations.

Ivanka Trump stepped down from her management role in the Ivanka Trump company when she took a job in her father's administration. She still owns part of the business.

-- Serena Dong contributed to this report.