BEIJING (Reuters) - Three labor activists in China who scrutinized a company making Ivanka Trump-branded shoes are being investigated on suspicion of providing industrial secrets to a foreign organization for money, state media reported on Wednesday.

China on Tuesday rejected a call from the U.S. State Department for the release of the activists saying they were being investigated on suspicion of interfering with a company’s “normal operation and production activities” and the illegal use of “professional surveillance equipment”.

The Paper, a Shanghai city government-backed newspaper, reported that police had found that the three got into “a certain factory” in Ganzhou city by applying for jobs there, after “receiving another person’s prompting”.

“They used specially bought hidden camera watches, professionally gathered internal documents on the factories’ production, hiring and salary standards as well as other industrial secrets, furthermore supplying these to relevant overseas organizations, with the purpose of obtaining funding support,” the Paper cited police as saying.

Neither the newspaper nor the foreign ministry identified the factory, nor did they mention any link to the Ivanka Trump brand, but the U.S.-based China Labor Watch organization said the three - Li Zhao, Su Heng and Hua Haifeng - had been looking into conditions at factories that produce shoes for the daughter of U.S. President Donald Trump and other Western brands.

The newspaper said Su and others had admitted to using job applications to “infiltrate” factories across the country to provide pictures of production to foreign organizations since 2010.

Authorities have not announced what charges the three might face but the newspaper said they were being held on the charge of illegally using hidden recording and filming devices.

Foreign ministry spokeswoman Hua Chunying said on Tuesday the case would be handled in accordance with the law and no country had the right to interfere in the judicial process.

On Monday, a spokeswoman for the U.S. State Department said labor activists have helped U.S. companies understand conditions in their China supply chains, “which can be essential in fulfilling their own responsibilities and holding Chinese manufacturers accountable under Chinese labor laws”.

A man who answered the telephone at the Ganzhou city police department declined to comment, saying he was not familiar with the case. Hua’s lawyer, Wen Yu, also declined to comment.

Deng Guilian, Hua’s wife, told Reuters she was not aware of the specifics of the case, though said her husband had told her he was not being mistreated.

China Labor Watch said Hua and Li had worked covertly at a shoe factory owned by the Huajian Group in the city of Dongguan. Su had worked at a related factory in Ganzhou, the group said.

Both factories produced Ivanka Trump-branded shoes, China Labor Watch said. The investigators had discovered evidence that workers’ rights had been violated, it said.

The Ivanka Trump brand, the White House and Ivanka Trump’s lawyer, Jamie Gorelick, have not responded to requests for comment on the case.