But the operating system at the Bushehr plant, which is to start up in weeks, has not been harmed, project manager Mahmoud Jafari told the official IRNA news agency.
The Stuxnet worm, which infected the personal computers of Bushehr staff, can seize control of entire industrial plants. Some experts say it is so complex it must have been created by a government, the British Broadcasting Corp. reported.
Stuxnet is tailored to exploit flaws in Siemens systems that manage water supplies, oil rigs, power plants and other utilities.
A team is now trying to remove the malicious software from affected computers, Jafari told IRNA.
"An electronic war has been launched against Iran", Mahmoud Liayi, head of the Information Technology Council, told the Iran Daily.
Liayi said the worm has infected about 30,000 IP addresses in Iran.