The Japanese government Thursday announced it will investigate reports of covert Chinese police stations within Japan’s borders. The announcement came after Asian human rights NGO Safeguard Defenders released reports claiming China has established over 100 police stations overseas.

Japanese Chief Cabinet Secretary Hirokazu Matsuno made the announcement at a press conference after a reporter asked about the Safeguard Defenders reports. Matsuno first stated, “the Japanese government would like to continue to gather information regarding this information” before claiming “activities which are violating our sovereignty should never be tolerated.” Matsuno then stated the Japanese government is “taking all necessary measures” to ensure Japan’s sovereignty is not threatened.

In response, Chinese Foreign Ministry Spokesperson Mao Ning stated at a press conference Thursday afternoon that “China has always adhered to the principle of non-interference in other countries’ internal affairs, strictly observed international law, and respected the judicial sovereignty of all countries. The so-called ‘overseas police stations’ simply do not exist.”

The South Korean government announced earlier in the week that it will also pursue investigations into the presence of Chinese overseas police stations. According to South Korean state news agency Yonhap News, the South Korean police began investigations into the reports on December 20.

The Safeguard Defenders reports claim that Chinese overseas police stations are meant to monitor and even repatriate Chinese citizens living overseas. The report claims the police stations violate the human rights of Chinese citizens by using threats of harm to family or property in China to force citizens to return to the country. The Ireland Department of Foreign Affairs ordered one such station to close in late October.