"These individuals, who infiltrated nuclear facilities and managed to win the confidence of the officials, were spying for foreign countries," Ali Mobacheri, the head of Tehran's revolutionary courts, told the government newspaper Iran.

"They are in prison and their trial is underway," he added.

He did not identify the accused, say when they were arrested or specify which countries they were allegedly spying for.

But the paper said that "in the past these individuals also spied for Iraq".

In August, Iran's Intelligence Minister Ali Yunessi announced the arrest of a number of "spies" who sent information on Iran's nuclear programme to foreigners.

He said the People's Mujahedeen, an armed opposition group based in Iraq that the regime in Tehran labels as "hypocrites", had played the central role in the espionage.

The group's political wing, the National Council for Resistance in Iran, in 2002 revealed two key nuclear sites Iran had been hiding, including an uranium-enrichment plant in Natanz.

And on Wednesday the group alleged Iran was hiding a uranium enrichment facility in Tehran and aims at getting the atomic bomb next year.

The group also said the father of the Pakistani atomic bomb, Abdul Qadeer Khan who has admitted to running an international nuclear smuggling network, delivered bomb designs and weapons-grade highly enriched uranium to Iran.

Iran insists that its nuclear activities are purely peaceful.

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