"This virus penetrated some fields. One of them was the oil sector," said Gholam Reza Jalali, who heads an Iranian military unit in charge of fighting sabotage. "Fortunately, we detected and controlled this single incident."
The Flame virus - a mix of cyberspy and hard-drive burglar - has been detected across the Middle East recently. But Iran's linkage to the oil network attack in April could mark its first major infiltration and suggests a significant escalation in attempts to disrupt Iran's key commercial and nuclear sites. Iran is one of the world's leading oil producers.
Two years ago, a virus called Stuxnet tailored to disrupt Iran's nuclear centrifuges caused some setbacks within its uranium enrichment labs and infected an estimated 16,000 computers, Iranian officials say. At least two other smaller viruses have been detected in nuclear and industrial centers.
The Flame program, however, is widely considered as a technological leap in break-in programming. Some experts also see the same high level of engineering shared by Stuxnet, which many suspect was the work of Israeli intelligence.
"It is very complex and very sophisticated," said Marco Obiso, cybersecurity coordinator at the U.N. International Telecommunication Union in Geneva. "It's one of the most serious yet."
Israel, a world leader in computer security, has never confirmed or denied any involvement in Stuxnet or other viruses that have hit Iranian networks.
Israel fears that Iran's nuclear program is geared toward developing a weapon that might be turned against it, and Israel itself is believed to have nuclear weapons.
Israeli leaders have repeatedly said that "all options are on the table," a phrase that is widely interpreted as meaning the possibility of a military strike and other measures that could include cyberwarfare.
Already, Iran and Israel have traded accusations of carrying out clandestine hits and attack conspiracies.
Iran alleges that Israeli agents are behind the slayings of at least five nuclear scientists and researchers since 2010. Earlier this month, Iran hanged a man convicted of carrying out one of the killings after allegedly being trained by Israel's Mossad spy agency. Israel denied any role.
Authorities in several countries, meanwhile, are investigating possible Iranian links to bombings and plots against Israeli targets and others, including a wide-ranging probe in Azerbaijan's capital Baku.
