A highly sophisticated computer worm which has many of the same characteristics of the virus used to attack Iran's nuclear programme has been discovered targeting companies in Europe. Experts say its code is so similar to the Stuxnet worm that attacked Iran, that it may have been engineered by the same people. The US and Israel were widely thought to be behind Stuxnet, which sent many of the centrifigues at Tehran's nuclear facilities spinning out of control. It took this kind of cyberwarfare to a new level. The new virus was discovered by Symantec, a leading cybersecurity firm, and has been called Duqu. Symantec would not disclose which firms had been targeted. The majority of the code is consistent with the Stuxnet code," said a spokesman for Symantec. "So this new worm either came from the authors of Stuxnet, or someone was given access to the Stuxnet source codes." Symantec suspects that Duqu may have been the first in a wave of new Stuxnet-style viruses, and that further sophisticated versions of it with a more aggressive purpose may emerge in the coming months. Stuxnet showed that cyberwarfare is developing fast, and is increasingly being thought of by states as a means of inflicting maximum damage with minimum risk. Earlier this year the Guardian revealed that the UK is developing its own "first strike" capability.