Iran has arrested several people it believes were spying on its nuclear facilities, a news agency quoted the intelligence minister as saying.
"We are always facing destructive activities by these [espionage] services, and, of course, we have arrested a number of nuclear spies to block the enemy's destructive moves," the website of state-run Press TV's reported.
The report gave no details and did not specify whether the arrests were linked to a virus Iran says infected computers at its Bushehr nuclear plant, which has yet to start working.
Citing the semi-official Mehr news agency, Press TV quoted intelligence minister Heydar Moslehi as saying "the enemy" had "sent electronic worms through the internet to undermine Iran's nuclear activities".
He said Iran was capable of fending off such an attack.
Some experts believe the Stuxnet virus may have been created to sabotage Iran's nuclear program, which some Western countries suspect may be aimed at building a bomb, which Iran has denied.
Iranian officials said the virus had affected personal computers of staff but had not affected operations at the plant.
Iran says it has complied with legal requirements and has a right to nuclear power.