Foreign Minister Toshimitsu Motegi voiced concern Tuesday over China's treatment of Muslim Uighurs and other minorities in the far west Xinjiang region.

China uses a system of mass surveillance and predictive-policing to round up "suspicious persons" to be sent to internment camps, according to internal documents obtained by the International Consortium of Investigative Journalists.

"We believe it is important that universal values in the international community, such as freedom, respect for basic human rights and rule of law are upheld in China," Motegi said when asked about the ICIJ's reports on the issue at a news conference.

He added that Japan was watching the human rights situation in the region with concern, noting that he'd relayed the same message in a meeting with his Chinese counterpart, Wang Yi, on Monday.

Beijing maintains that the issue is a domestic matter in which other countries should not become involved.

According to the internal Communist Party documents, China uses a system powered by artificial intelligence to analyze personal information and flag individuals for investigation. Beijing cites the threat of "terrorism" and "extremism" as grounds for sweeping surveillance and mass detention.

The system identified over 24,400 Xinjiang residents as "suspicious persons" over a one-week period in June 2017, the documents showed, of which more than 15,600 were sent to internment camps for supposed "education and training."