By WILLIAM YONG

TEHRAN — Iran has arrested an unspecified number of “nuclear spies” in connection with a damaging worm that has infected computers in its nuclear program, the intelligence minister, Heydar Moslehi, said Saturday.

Mr. Moslehi also told the semiofficial Mehr news agency that the ministry had achieved “complete mastery” over government computer systems and was able to counter any cyberattacks by “enemy spy services.”

Iran confirmed last week that the Stuxnet worm, a malicious self-replicating program that attacks computers that control industrial plants, had infected computers in its nuclear operations. Officials said it had been found in personal computers at the Bushehr nuclear plant, a power generator that is not believed to be part of a weapons program, and that it had not caused “serious damage” to government systems.

While the origins of the worm remain obscure, many computer security experts believe it was created by a government with the intent of sabotaging Iran’s nuclear program, which Western countries believe is aimed at creating a nuclear weapon. The United States and Israel have cyberwarfare programs and both countries have sought to undermine Iran’s nuclear enrichment program, but neither has commented on the Stuxnet worm.

Iran has portrayed the worm as a cyberattack by Western powers and Israel intended to derail the country’s nuclear program, which the government says is for peaceful purposes.

“All of the destructive activities perpetrated by the oppressors in cyberspace will be discovered quickly and means of combating these plans will be implemented,” Mr. Moslehi said. “The intelligence Ministry is aware of a range of activities being carried out against the Islamic Republic by enemy spy services.”

He provided no further details on the arrests, which could not be independently verified.

Hamid Alipour, an official at the state-run Iran Information Technology company, has said that the worm is spreading. “This is not a stable virus,” he said last week. “By the time we started to combat it three new variants had been distributed.” He said his company hoped to eliminate it within “one to two months.”