Data from various Japanese government entities has reportedly been stolen by hackers that gained access to Fujitsu's ProjectWEB platform.
Fujitsu's software-as-a-service platform has since been taken down and the Japanese tech giant is currently investigating the scope of the attacks.
"Fujitsu can confirm unauthorised access to ProjectWEB, a collaboration and project management software, used for Japanese-based projects. Fujitsu is currently conducting a thorough review of this incident, and we are in close consultation with the Japanese authorities," Fujitsu told ZDNet.
"As a precautionary measure, we have suspended use of this tool, and we have informed any potentially impacted customers."
Among the impacted government entities are the Ministry of Land, Infrastructure, Transport, and Tourism; the Cabinet Secretariat; and Narita Airport, Japan's public broadcaster NHK said in a report.
The land, infrastructure and transport ministry reportedly had at least 76,000 email addresses of its employees and business partners leaked, along with data on the ministry's internal mail and internet settings.
Meanwhile, the Cabinet Secretariat's cybersecurity centre reportedly had data on the centre's information system stolen from several of its offices.
Narita Airport air traffic control data was also stolen, the report said, which has prompted the Cabinet Secretariat's national cybersecurity centre to issue alerts about the use of the Fujitsu software.
In the past three weeks alone, one of the US' largest pipeline operators and healthcare institutions across Canada, New Zealand, and Ireland have faced cyber attacks.
Updated at 11:17am AEST, 28 May 2021: added comment from Fujitsu.