A Chinese company that makes shoes for Ivanka Trump’s brand on Thursday said it didn’t know the whereabouts of three activists who were detained or have gone missing while investigating claims of excessive overtime and low pay against the business.

Three employees of China Labor Watch, a New York-based nonprofit that has been documenting poor working conditions in China for 17 years, were covertly looking into claims of worker abuse at Huajian Group factories in the Chinese cities of Ganzhou and Dongguan.

One of the men, Hua Haifeng, has been arrested on a charge of illegal surveillance, but two others, Li Zhoa and Su Heng, are missing.

A spokeswoman for Huajian said the company had stopped making Trump’s shoes months ago and disputed the accounts about the investigators as “untrue reports.”

“We are shocked,” Long Shan told the Associated Press. “As a renowned global media outlet, you have put out many untrue reports not based on facts and without our consent.”

She said Hua began working at the Dongguan factory on May 20 but left after less than a week, Su started working at the Ganzhou factory on April 28 but quit a short time later.

Long said she didn’t know where they were now.

Li Qiang, the executive director of China Labor Watch, said he doesn’t know what happened to Su and Li.

“By coming to Huajian to work, they are Huajian employees. Huajian staff must comply with China’s laws and regulations and Huajian’s rules,” she told the AP.

Long also said at least one of the men “used methods like taking photographs and video to obtain the company’s trade secrets, which is not in line with the company’s regulations. Our company has the right to hold him accountable.”

Huajian makes millions of pairs of shoes each year for some of the world’s top brands and producers between 100,000 and 200,000 for Ivanka’s company.

Marc Fisher Footwear, the company that licenses her name, told CBS News, “We were unaware of the allegations and will look into them immediately.”