Japan's communications ministry has issued a second round of administrative guidance to the operator of the Line messaging app, saying its measures to prevent leaks of user data are unsatisfactory.

Last month, LY Corporation received initial guidance over a significant breach of user data.

The company submitted prevention measures on April 1, including a review of its outsourcing contract with the South Korean IT firm Naver.

The communications ministry found the measures inadequate and conducted a follow-up administrative guidance session on Tuesday.

The ministry cited insufficiencies in safety management, especially regarding Naver, and uncertainties over whether a comprehensive review of the entire group's security governance framework would take place.

It urged LY to conduct a fundamental review into the supervision of outsourcing contractors, and expedite the reassessment of capital ties with Naver, which finances LY's parent company.

Communications minister Matsumoto Takeaki told reporters on Tuesday he wants LY to take seriously the fact that its response to the previous guidance was insufficient, and implement thorough measures.

The ministry has requested that LY submit a detailed report on its review status by July 1.