Mitsubishi Heavy Industries (MHI), Japan’s biggest weapon maker, said it’s servers were hacked after it found viruses on 80 machines.

The Japanese Government has insisted it carry out an investigation following local media reports of the attack.
 

Reports said Japan's defence minister Yasuo Ichikawa told a news conference the cyber attackers had not succeeded in accessing any important information but MHI would be instructed "to undertake a review of their information control systems".

"The ministry will continue to monitor the problem and conduct investigations if necessary,"Mr Ichikawa added.

 

Missile systems, submarine and nuclear power plant systems were targeted. The attacks came from outside the company’s IT network, said MHI.

The Chinese Government denied any involvement after local Japanese media said a Chinese language script was identified though no official comment on who might be responsible came from MHI or Japanese officials. 

"China is one of the main victims of hacking... Criticising China as being the source of hacking attacks not only is baseless, it is also not beneficial for promoting international co-operation for internet security,"foreign ministry spokesman Hong Lei said.

MHI confirmed that 45 of its servers and 38 computers were infected by at least eight viruses.

The viruses targeted a shipyard in Nagasaki, where destroyers are built, and a facility in Kobe that manufactures submarines and parts for nuclear power stations, public broadcaster NHK reported.

A plant in Nagoya, where the company designs and builds guidance and propulsion systems for rockets and missiles, was also reportedly compromised.

MHI said it had consulted the Tokyo police department and was carrying out an investigation alongside security experts, which should be concluded by the end of the month.

A second defence contractor, IHI, which supplies engine parts for military aircraft, said it had also been targeted.