The head of the Iranian Passive Defence Organisation, Gholam Reza Jalali, described the software as an "espionage virus."

"Luckily, our young specialists detected the virus and sent it to a lab for testing," Jalali said.

He did not elaborate on when the virus, dubbed Stars, was detected or what facilities it targeted but said it "failed to do any serious damage."

In September 2010, the Iranian authorities announced that a virus, named Stuxnet, had attacked computers of employees at the Bushehr nuclear power plant but had not affected the running of the plant.

Iranian President Mahmoud Ahmadinejad blamed the Stuxnet attack on Iran's "enemies" trying to undermine the country's disputed uranium enrichment facilities.

Western powers suspect Iran of building nuclear weapons under the guise of a peaceful nuclear program, an accusation Tehran strongly denies.