The Islamic Republic announced on Tuesday that it had succeeded in terminating the spread of a data-deleting virus targeting computer servers in its oil sector, and hoped to have all systems back and running within days.
Hamdolah Mohammadnejad, a deputy oil minister heading up a crisis committee to counter the "cyber attack," told the official IRNA news agency that the virus's impact had been limited by rapid action.
"We shut computers connected to these servers temporarily and fortunately we were able to stop its spread. Thus no information or data were harmed," he said. "We are investigating the causes of these cyber problems and in the next two to three days we hope the problems will be solved," he added.
Reports on Monday said Iran had disconnected several of its computers from the Internet to curb the virus, including ones running its main oil export terminal on Kharg Island in the Gulf, according to AFP.
Mohammadnejad stressed to IRNA that Iran's oil facilities were continuing to operate despite the digital assault, and that back-ups existed of any data that could have been affected. He said the malware had attacked "a number of National Iranian Oil Company servers ... but cyber security experts quickly restrained it."
The websites of the Iranian oil ministry (www.mop.ir) and the National Iranian Oil Co (www.nioc.ir) were back on-line on Tuesday, after being inaccessible for many hours after the virus first struck on Sunday.
Iranian officials and media made no accusations so far over who might have been behind the attack.