TOKYO, Sept 20 (KUNA) -- Information about the working of the computer system of Mitsubishi Heavy Industries Ltd., Japan's largest defense contractor, has leaked through the infection of servers and computers with viruses, Kyodo News Agency reported Tuesday, citing sources close to the matter.

Mitsubishi Heavy had found information about its computer network system, such as IP addresses, had leaked, and further cyber attacks on its computer system could be carried out based on the leaked data, the sources told Kyodo. The infected servers had been forcibly connected to overseas websites, the report said.

On Monday, Mitsubishi Heavy said it found 45 servers and 38 computers were infected with eight types of viruses at 11 company facilities in Japan, including its headquarters in Tokyo, shipbuilding yards in Nagasaki and Kobe, and Nagoya Guidance & Propulsion Systems Works in Aichi Prefecture. The Aichi facility produces rocket engines and missile defense components, while the Nagasaki shipyard makes Self-Defense Forces destroyers and the Kobe shipyard nuclear-powered submarines. The cyber attack on Japan's top defense contractor immediately is the focus of considerable government concern. Chief Cabinet Secretary Osamu Fujimura said Tuesday the government will collect information and deal with the cyber attacks not only on government systems but also on private company networks. Defense Minister Yasuo Ichikawa said his ministry will instruct Mitsubishi Heavy to tighten the security of its computer systems. IHI Corp., which manufactures aircraft engines used by the Defense Ministry, also said Tuesday its computer system has come under a cyber attack, but that the system has not been infected with viruses and no data leak has occurred.