Iranian security services have arrested several suspected spies in the southern province of Bushehr where the country's first nuclear power plant is located, the semi-official Fars news agency reported on Tuesday.
Iran has repeatedly cited signs of what it calls foreign plots to sabotage its nuclear programme, which world powers fear could be put to developing an atomic bomb capability and are seeking to curb through high-level negotiations, with a deadline of Nov. 24 for an accord.
The Islamic Republic says it is developing nuclear energy only for electricity and medical treatments.
"Thanks to the vigilance of Intelligence Ministry forces who monitor the moves of the foreign intelligence services, some agents who intended to carry out surveillance and intelligence gathering for foreigners have been arrested," Intelligence Minister Mahmoud Alawi Alawi told Fars, without elaborating.
He said Bushehr province was Iran's nuclear hub and therefore "has a special position at the national level".
Although the West suspects Iran has tried to develop the means to assemble a nuclear weapon behind the facade of a civilian atomic energy programme, the Russian-built Bushehr nuclear power station on the country's Gulf coast is not itself deemed to be a serious proliferation risk by Western states.
In 2010, Iran's uranium enrichment facilities were temporarily impaired by a virus known as Stuxnet, which was widely believed to have been developed by the United States and Israel, although no government took responsibility for it.
In March of this year, pumps at Iran's planned Arak reactor, seen by the West as a potential source of plutonium that could fuel nuclear bombs, were subjected to a failed sabotage attempt, Iranian media quoted a senior official as saying.
Iran and the world powers - the United States, Russia, China, Britain, France and Germany - are trying to negotiate an end to a decade-old standoff that has led to damaging economic sanctions imposed on the Islamic Republic.
The election last year of moderate Hassan Rouhani as Iranian president led to an interim diplomatic accord last November under which Tehran has curbed some sensitive aspects of its enrichment activity in exchange for limited sanctions relief.
It remains unclear whether the two sides will meet the self-imposed Nov. 24 deadline for a permanent deal that would scale back Tehran's nuclear capacity to remove its potential for bombmaking in exchange for a phasing-out of all sanctions.