Government officials have refused to confirm or deny reports that key Whitehall departments have been attacked by computer hackers from the Chinese military.

The Foreign Office and the Ministry of Defence have both come under attack by hackers, some of whom are thought to be part of the China’s People’s Liberation Army, according to reports in the Guardian newspaper.

An outage that hit part of the House of Commons computer system last year was attributed by officials to an organised Chinese hacking group, the paper said.

But both the Ministry of Defence and the Foreign Office refused to comment on the reports. “We do not comment on security issues,” a Foreign Office spokesperson said.

The claims of attacks on UK government computer networks follow leaked reports of an internal investigation into attacks on the US Department of Defence. Officials have said the inquiry found evidence that the People’s Liberation Army was behind the hacks into the Pentagon network, dubbing the increasing number of attacks on US government systems “Titan Rain”.

The Pentagon shut down its systems, taking around 1,500 computers offline, following the cyber attack in June.

Angela Merkel, Germany's chancellor, has also questioned Chinese premier Wen Jiabao about infiltration of German government networks.

But China has denied involvement in the spate of attacks, saying the reports reflect “a cold war mentality”. A spokesperson in the US said: “The Chinese government has consistently opposed and vigorously attacked according to the law all Internet-wrecking crimes, including hacking.”