Countries are already using cyber warfare techniques to attack each other and need to be vigilant round the clock to protect computer systems, the head of Britain's communications spy agency says.

Iain Lobban, the director of the Government Communications Headquarters (GCHQ), said British government systems are targeted 1,000 times each month.

"Cyberspace is contested every day, every hour, every minute, every second," he said late Tuesday in a rare speech. His remarks, to a London audience, were published Wednesday.

The Internet lowered "the bar for entry to the espionage game," he said. Its expansion increased the risk of disruption to infrastructure such as power stations and financial services.

"The threat is a real and credible one," said Lobban, whose GCHQ agency, a big eavesdropping operation similar to the National Security Agency in the United States, handles operations such as intelligence-gathering and code-busting.

Politicians and spy chiefs in Britain and around the world have increasingly been warning about the growing cyber threat.

The issue came to the fore last month when security experts suggested that the Stuxnet computer worm that attacks a widely used industrial system could have been created by a state to attack nuclear facilities in Iran.

"It is true we have seen the use of cyber techniques by one nation on another to bring diplomatic or economic pressure to bear," Lobban told the International Institute for Strategic Studies, without giving specific details.

A recent parliamentary report said GCHQ had indicated that states such as Russia and China posed the greatest threat of electronic attack on Britain.

The United States is currently setting up a Cyber Command to defend defense networks and mount offensive cyber strikes, and Lobban said there needed to be agreement on the "proper norms of behavior for responsible states in cyber space.

The growth of electronic crime was "disturbing," costing the British economy billions of pounds, he said.

"Just because I, as a national security official, am giving a speech about cyber, I don't want you to take away the impression that it is solely a national security or defense issue," he said. "It goes to the heart of the our economic well-being and national interest."


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