A report in August revealed that a five-year campaign compromised networks in 72 major organisations around the world, including several governments

Japan’s Foreign Ministry and foreign diplomatic missions have come under cyber attack since June, the government said Wednesday.

Computers at embassies and other diplomatic offices abroad were attacked in a number of countries, including those in North America and Asia, the Kyodo News agency reported, citing unnamed sources with knowledge of the attacks.

Some overseas offices found their computers infected with viruses but no classified information has been leaked, Chief Cabinet Secretary Osamu Fujimura said at a news conference.

The ministry was investigating the extent of the damage caused by the assault and was trying to identify the culprits, Kyodo said.

The lower house of the Diet on Tuesday reported a security breach of a server to the police. The server came under attack through the computers of three lawmakers. Their computers were found to have been infected with viruses, but no leakage of data had been confirmed, the chamber said.

Local media reported a month ago that Japan’s major defence contractors, including Mitsubishi Heavy Industries Ltd, suffered cyber attacks.

Information about military aircraft and nuclear power plants linked to Mitsubishi Heavy, the nation’s largest defence contractor, might have been read by hackers, Kyodo reported, citing unnamed government sources.