Iran says it has found a way to "control" the computer malware Duqu, which is similar to Stuxnet virus which in 2010 attacked its nuclear programme and infected more than 30,000 computers.
"The software to control the (Duqu) virus has been developed and made available to organisations and corporations" in Iran, head of civil defence Brigadier General Gholamreza Jalali told the official IRNA news agency.
"The elimination (process) was carried out and the organisations penetrated by the virus are under control ... The cyber defence unit works day and night to combat cyber attacks and spy (computer) virus," he added.
Duqu infections have been reported in a dozen countries including Iran, France, Britain and India, US computer security firm Symantec said in mid-October.
The virus takes advantage of a previously unknown vulnerability in a Windows font-parsing engine to plant malicious code in the heart of a computer system, according to Microsoft.
Similarities between Duqu and a malicious Stuxnet worm have prompted speculation that the same culprits might be involved, though no links have been proven.
Duqu is similar to Stuxnet but is designed to gather intelligence for future attacks on industrial control systems.
Stuxnet was designed to attack computer control systems made by German industrial giant Siemens and commonly used to manage water supplies, oil rigs, power plants and other critical infrastructure.
Most Stuxnet infections have been discovered in Iran, giving rise to speculation it was intended to sabotage nuclear facilities there. The worm was crafted to recognise the system it was designed to attack.
The New York Times reported in January that US and Israeli intelligence services collaborated to develop the computer worm to sabotage Iran's efforts to make a nuclear bomb.