One man has been arrested and two others are missing after investigating a Chinese company making Ivanka Trump-branded shoes.
Hua Haifeng was working undercover for China Labor Watch, a New York-based advocacy group.
Li Qiang, the group´s executive director, said Hua was detained in Jiangxi province on suspicion of illegally using eavesdropping equipment.
The men were probing alleged labor abuses at two Chinese factories which make shoes for Ivanka Trump and other brands.
They are run by the Huajian Group, one of the world’s largest manufacturers of women’s footwear.
"We appeal to President Trump, Ivanka Trump herself, and to her related brand company to advocate and press for the release our activists," China Labor Watch said in the email to Reuters.
The Ivanka Trump brand declined to comment on the detention. The White House did not immediately reply to a request for comment.
A spokeswoman for Marc Fisher Footwear, which licenses the Ivanka Trump brand for shoes made in China by Huajian said, “We were unaware of the allegations against” the Chinese manufacturer and would look into them immediately.
Li said in 17 years of activism, including investigations of hundreds of Chinese factories, this was the first time anyone from his group had been arrested on suspicion of having committed a crime.
President Trump has recently secured more than 75 trademarks in China.
The human rights group Amnesty International´s China researcher William Nee, has joined in calls to free the activists, “Hua Haifeng, Li Zhao and Su Heng must be released if they are being held solely for investigating possible labor abuses at factories making shoes for Ivanka Trump’s label."
Dozens of campaigners have been arrested in the past year, prompting concerns about a toughening of Beijing's stance.
China routinely rejects foreign criticism of its human rights record and says it is a country ruled by law.