President Mahmoud Ahmadinejad admitted Monday that "several" uranium enrichment centrifuges were damaged by "software installed in electronic equipment," amid speculation Iran's nuclear activities had come under cyberattack.

"They were able to create problems on a limited basis for some of our centrifuges by software installed in electronic equipment," Ahmadinejad told reporters when asked whether Iran's nuclear programme had been affected.

"Our specialists stopped that and they will not be able to do it again," he added without elaborating on the software thought to have been

Symantec says Stuxnet worm aimed to disrupt electrical motor controls, like those used by gas centrifuges to enrich uranium; Stuxnet, considered by many security researchers to be the most sophisticated malware ever, targeted Windows PCs that managed large-scale industrial-control systems in manufacturing and utility companies

Researchers have uncovered new clues that the Stuxnet worm may have been created to sabotage Iranian attempts to turn uranium into atomic bomb-grade fuel.

According to Eric Chien, one of three Symantec researchers who have dug into Stuxnet, the worm targets industrial systems that control very high speed electrical motors, such as those used to spin gas centrifuges, one of the ways uranium can be enriched into fissionable material.