A US State Department official dismissed on Tuesday the possibility of a cyber war between China and the United States, while calling for building mutual confidence to avoid such an eventuality.

"People talk about cyber war. Frankly, I don't think we've really seen it," said Christopher Painter, coordinator for cyber issues at the State Department.

"Or to the extent we've seen it, it's much more overemphasized in terms of the threats we actually see out there," Painter said, admitting that such concerns exist.

Claims that China launched cyber attacks against the US flared up earlier this year, centering on intrusions into the websites of US military contractors and the Google e-mail accounts of US officials. Beijing has denied any government involvement.

Painter said there were cyber attacks on the US, but noted that it was difficult to locate the attackers.

Washington is seriously concerned about cyber attacks and is prepared to use force as it considered them an act of war, former US defense secretary Robert Gates said in June.

Just before the US-led strikes in Libya in March, the Obama administration intensely debated whether to start a cyber offensive to disrupt and even disable the libyan government's air-defense system, which threatened allied warplanes, reported the New York Times.

The goal would have been to break through the firewalls of the Libyan government's computer networks to sever military communications links and prevent early-warning radars from gathering information and relaying it to missile batteries aimed at NATO warplanes, according to the report.

The plan failed eventually amid concerns of setting a precedent for other nations to carry out such offensives of their own.

Painter suggested countries exchange strategies and information to build confidence over the long term, "so you never get to the point of a cyber conflict or even a larger conflict".

Vice-Foreign Minister Cui Tiankai told foreign reporters ahead of a meeting with US officials in Hawaii in June that China and the US might suffer from cyber attacks, but they were in no way directed by either government.

Both countries were in fact already discussing the problem of hacking during their regular strategic consultations, Cui said.

"The international community ought to come up with some rules to prevent this misuse of advanced technology," Cui added.

Efforts to establish international rules in this advanced field have already started. In May, G8 Summit host country France put the Internet on the agenda for the first time in a bid to improve regulation of the cyber world.

China, Russia, Tajikistan and Uzbekistan in September also submitted a draft code of conduct for information security for discussion at the United Nations General Assembly.

Any such agreement remains a distant prospect because nations lack common legal standards in cyberspace and information security is closely connected with national interests, said Wen Weiping, an expert with the School of Software and Microelectronics at Peking University.

But he also said cooperation in areas of mutual interest regarding cyberspace should be pushed forward. "Only through determined cooperation can we win the war against hackers to secure the Internet."