Experts at Iran's nuclear agency are trying to disable a complex computer virus that has attacked the country's industrial sites and appears to be aimed at shutting down its Bushehr nuclear plant, which was due to go online next month.

According to the semi-official ISNA news agency, officials at Iran's nuclear agency have met to determine how to combat the computer worm, called Stuxnet, which can take over systems that control the inner workings of industrial plants.

The ISNA report said the virus had spread throughout Iran, but did not name the sites affected.

Computer security experts who have studied Stuxnet since it emerged two months ago believe it was designed specifically to attack the Siemens-designed working system of the Bushehr plant and appears to have infected the system via the laptops and USB drives of Russian technicians who had been working there.

Western experts say the worm's sophistication – and the fact that some 60% of computers infected appeared to be in Iran – pointed to a government-backed attack.

Although the worm has turned up in other countries since first appearing in July – including Indonesia and the US – the frequency of its appearance in Iran has suggested the country was the intended victim of the cyber-warfare attack, with some analysts speculating that Israel might be behind it.

The Russian-built nuclear plant will be internationally supervised, but world powers remain concerned that Iran wants to use its civil nuclear power programme as a cover for making weapons.

While there have been no reports of damage or disruption at any Iranian nuclear facilities, last Tuesday's meeting signalled a high level of concern about the worm among Iran's nuclear officials. The Stuxnet worm has surprised experts because it is the first one created to take over industrial control systems, rather than just steal or manipulate data.