Iran has been targeted by a new computer virus in a "cyber war" waged by its enemies, according to a senior military official of the Islamic republic.

Gholam Reza Jalali, commander of civil defence, told the semi-official Mehr news agency on Monday that the new virus, called Stars, was being investigated by experts.

"Certain characteristics about the Stars virus have been identified, including that it is compatible with the [targeted] system," he said.

He said that Iranian experts were still investigating the full scope of the malware's abilities.

Jalali played down the impact of Stars, but said it is "harmonious" with computer systems and "inflicts minor damage in the initial stage and might be mistaken for executive files of governmental organisations".

He did not say what equipment or facilities the virus targeted, or when experts first detected it.

Stars is the second serious computer worm to hit Iran in the past eight months.

Iran was hit with another computer worm, Stuxnet, last year, reportedly designed to hurt Iran's controversial nuclear programme.

The country has accused the US and Israel of launching Stuxnet, which was publicly identified last June and reportedly mutated and infected at least 30,000 computerised industrial equipment in the following months.

The existence of Stuxnet became public knowledge around the time that Iran began loading fuel into Bushehr, its first nuclear reactor, last August.

Iran said in September that staff computers at Bushehr had been hit but that the plant itself was unharmed.

Bushehr is still not operational, having missed several start-up deadlines. This has prompted speculation that Stuxnet damaged the plant.

But Iran said its scientists discovered and neutralised the malware before it could cause serious damage.