Messaging app provider Line Corp. said Wednesday its app users' personal information had been accessed by technicians in China without users being informed as required by law.

Line, whose app is used by over 86 million of Japan's some 126 million people, says in its data protection guideline that customers' personal information can be transferred overseas. But it does not specify the name of any foreign country despite being required to do so under a legal change last year.

Line said a Chinese affiliate entrusted to develop artificial intelligence technologies had access to its database at least 32 times.

Four technicians of Line's affiliate company in China were able to see users' names, phone numbers and email addresses along with messages reported by users as inappropriate from around the summer of 2018. Conventional messages were not read as they were encrypted.

"We are very sorry for causing anxiety and concerns due to our inadequate explanations," the app operator said in a statement, adding that some of its app users' personal information stored in Japan was able to be accessed from its operating bases abroad, a system in place to improve its services.

Line said it has confirmed no improper data use and blocked access to its database from China in February.

The app operator said it has reported the matter to the government's Personal Information Protection Commission and will soon set up a third-party panel to investigate the incident.

Chief Cabinet Secretary Katsunobu Kato said at a press conference that the government will appropriately respond to the matter after confirming details. The government commission also said it will look into the case, including whether Line properly supervised the affiliate.

The requirement to specify to which countries data is transferred was introduced under a revision to the personal information protection law in June last year.

The Line app has been increasingly used in Japan as a main social communications tool and is also popular in Taiwan, Thailand and Indonesia.

"It is a big problem to offer customers' personal information including names and phone numbers to a third party overseas without the consent of users," said Noboru Matsuzawa, manager of the social improvement and life design research department at the NLI Research Institute.

He also noted that the Communist-led government in China can collect a broader range of information than a democratic country like Japan, making it "very bad" for Line to have allowed outsiders there to read inappropriate messages reported by its users.

Line launched its messaging app in June 2011 and merged with Z Holdings Corp., operator of Yahoo Japan internet services, on March 1 to globally expand its online service business and compete with U.S. and Chinese tech giants.

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