China said Wednesday its authorities have held 35 Japanese nationals in criminal custody late last month on suspicion of fraud.
The confirmation came after a source involved in Japan-China relations said they have been detained for alleged involvement in telephone scams, making calls from China to people in Japan and talked them into transferring large sums of money through banks.
Chinese Foreign Ministry spokesman Geng Shuang, who provided the confirmation, said police took them into custody on June 30.
A Japanese government source said Chinese authorities notified Japan on July 3 that the suspects were detained in Fujian Province, southeastern China.
Criminal custody is often a step taken by Chinese police before arresting a person. The 35 Japanese may be officially arrested later.
Japan and China have been negotiating an extradition treaty since 2010 but have yet to seal a pact. Japan would need to negotiate through diplomatic channels if it wants the suspects extradited.
China has detained at least 12 Japanese nationals since 2015 over allegations such as espionage, with the Japanese government expressing concern in those cases over the lack of transparency and explanation by Beijing.
The bilateral source said, however, that the latest suspected fraud case is different from those detentions in nature.