Japan defence firm Mitsubishi Heavy in cyber attack

Japan's top weapons maker has confirmed it was the victim of a cyber attack reportedly targeting data on missiles, submarines and nuclear power plants.

Mitsubishi Heavy Industries (MHI) said viruses were found on more than 80 of its servers and computers last month.

But the firm said it has not detected any leaks of sensitive information.

Japan's defence ministry has demanded MHI carry out a full investigation. Officials were angered after learning of the breach from local media reports.

All government contractors are obliged to inform ministers promptly of any breach of sensitive or classified information.

"It's up to the defence ministry to decide whether or not the information is important. That is not for Mitsubishi Heavy to decide. A report should have been made," a defence ministry spokesman was quoted by Reuters as saying.

Better protection

The online attacks - which are believed to be the first of their kind against Japan's defence industry - originated outside the company's computer network, MHI said.

They have been described as "spear attacks" - when hackers send highly customised and specifically targeted messages aimed at tricking people into visiting a fake webpage and giving away login details.

MHI has confirmed its servers and computers have been 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, which supplies engine parts for military aircraft, said it had also been targeted.

IHI said it had been receiving emails containing viruses for months, but its security systems had prevented infection.

There are also reports that Japanese government websites, including the cabinet office and a video distribution service, have been hit by denial-of-service attacks.

Last month, a Japanese defence white paper urged better protection against cyber attacks after US defence contractors were hit by a spate of assaults.