The next world war could take place in cyberspace, the UN telecommunications agency chief warned on Tuesday as experts called for action to stamp out cyber attacks.

"The next world war could happen in cyberspace and that would be a catastrophe. We have to make sure that all countries understand that in that war, there is no such thing as a superpower," Hamadoun Toure said.

"Loss of vital networks would quickly cripple any nation, and none is immune to cyber attack," added the secretary-general of the International Telecommunications Union during the ITU's Telecom World 2009 fair in Geneva.

Toure said countries have become "critically dependent" on technology for commerce, finance, health care, emergency services and food distribution.

"The best way to win a war is to avoid it in the first place," he stressed.

As the internet becomes more linked with daily lives, cyber attacks and crimes have also increased in frequency, experts said.

Such attacks include the use of "phishing" tools to get hold of passwords to commit fraud, or attempts by hackers to bring down secure networks.

Individual countries have started to respond by bolstering their defences.

US Secretary for Homeland Security Janet Napolitano said last Thursday that she has received the green light to hire up to 1000 cyber security experts to ramp up the United States' defences against cyber threats.

South Korea has also announced plans to train 3000 "cyber sheriffs" by next year to protect businesses after a spate of attacks on state and private websites.

Warning of the magnitude of cyber crimes and attacks, Carlos Solari, Alcatel-Lucent's vice-president on central quality, security and reliability, told a forum here that breaches in e-commerce are now already running to "hundreds of billions".

But one of the most prominent victims in recent years has been the small Baltic state of Estonia, which has staked some of its post Cold War development on new technology.

In 2007 a spate of cyber attacks forced the closure of government websites and disrupted leading businesses.

Estonian Minister for Economic Affairs and Communications Juhan Parts said in Geneva that "adequate international cooperation" was essential.