Japan's national cybersecurity center and two ministries said Wednesday that unauthorized access to an information-sharing tool developed by Fujitsu Ltd., which is contracted to oversee its computer systems, has led to a data breach.

The leaked information includes at least 76,000 email addresses of government officials and external parties, such as members of expert panels, as well as study materials on creating a digital government, according to the affected foreign and transport ministries.

The government's National Center of Incident Readiness and Strategy for Cybersecurity, or NISC, said that the product names and maintenance schedules of computers that make up its system had been leaked to external parties.

All three government agencies have said that their internal systems are operating normally, and no unauthorized access has been detected.

Chief Cabinet Secretary Katsunobu Kato, at a press conference the same day, expressed his intention to take all possible measures against cyberattacks, saying, "Various attacks on infrastructure are expected during the Tokyo Olympics."

Fujitsu said Tuesday that the data of several of its corporate clients had been compromised due to unauthorized access of the tool, which is used to share information between internal and external parties of a company.

Narita International Airport Corp., which also uses the tool, has said that it is highly likely that data related to the airport's flight information management system has been leaked.

NISC on Tuesday warned government agencies and infrastructure providers using the tool to enforce measures against potential data leaks.