A cyber security researcher says Iran's new Bushehr power plant may be the intended target of a sophisticated computer virus attack.
German researcher Ralph Langner says the virus, known as Stuxnet, may have already hit its target, but the results are not known yet.
Cyber security experts describe Stuxnet as a "super weapon" that appears to be specifically designed to target installations such as power plants.
Experts say they first became aware of it in June. They say their analysis of Stuxnet shows it can get into computer systems that are not connected to the Internet for security reasons.
They say Stuxnet can take control of computer systems on its own.
Britain's MailOnline on Thursday quoted security experts as saying their analysis indicates Iran has been hardest hit by Stuxnet. They say nearly 60 percent of the computers discovered to be infected with the virus are in the Islamic republic.
In August, Iran announced the start-up of the Bushehr facility, which was built with help from Russia.