A man investigating abusive working conditions at the Chinese factory that makes Ivanka Trump-brand shoes has gone missing, and two others have been arrested, according to an advocacy group.

Chinese officials are accusing Hua Haifeng of illegal surveillance for his work secretly keeping tabs on production at the facility, according to wife Deng Guilian, who got a call Tuesday saying she could no longer speak with her husband.

Hua and two others, Li Zhao and Su Heng, were undercover at the Ganzhou Huajian International Shoe City Co. factory in Jiangxi province, documenting minimum-wage violations and brutally long work days when they went missing, according to China Labor Watch Executive Director Li Qiang, who lost contact with the men over the weekend.

“They must be held either by the factory or the police to be unreachable,” Li said. “Our plan was to investigate the factory to improve the labor situation. But now it has become more political.”

During their final phone conversation on Saturday, Hua told Li that police had made the unprecedented move of asking him to stop investigating the Huajian factory.

The company makes 10,000 to 20,000 pairs of shoes a year for Ivanka Trump’s brand — a fraction of the 20 million pairs the company produces a year — as well as Marc Fisher, Nine West and Easy Spirit merchandise.

White House spokeswoman Hope Hicks referred questions to Ivanka Trump’s brand, but the brand declined to comment.

Abigail Klem, who took over day-to-day management when the first daughter took on a White House role as presidential adviser, has said that the brand requires licensees and their manufacturers to “comply with all applicable laws and to maintain acceptable working conditions.”

A spokeswoman for the factory did not respond to questions Tuesday.

The New York-based labor-watch group has also exposed workplace violations at Chinese Apple AAPL, -3.17% factories and the factories of suppliers to Samsung 005930, -0.33% and Walt Disney DIS, -1.22% .

The group has previously accused factories making Ivanka Trump-brand shoes of paying workers as little as $1 per hour and forcing them to work minimum 12½-hour days.

This report originally appeared on NYPost.com.