At least four people have been arrested in Iran for trying to sabotage a nuclear site, an Iranian official was quoted by Iranian media as saying.

The head of Iran's Atomic Energy Organisation, Ali Akbar Salehi, said on Sunday that officials had monitored and then arrested a "number of saboteurs" before they could carry out their plan.

"Four of these individuals were caught red-handed and their interrogations are ongoing," he said, according to the Mehr news agency.

He did not identify which nuclear site they were planning to damage or when those detained were arrested.

In August last year, saboteurs blew up power lines supplying Iran's underground uranium enrichment plant at Fardo outside the central city of Qom.

In 2010, a US cyber attack, reportedly carried out in collaboration with Israel, hit Iran's nuclear facilities.

The Stuxnet virus was tailored specifically to target uranium enrichment facilities.

"There are still viruses out there but we have taken the necessary measures," Mr Salehi said.

"Since we uncovered the Stuxnet virus, we have reinforced our protection systems and a special unit has been set up."

Israel, widely believed to be the region's only nuclear-armed state, sees Iran's atomic work as a military threat and has said it will attack Iran's nuclear sites if it does not end its program.

Iran says its nuclear work is purely peaceful.

Iran accuses Israel and the West of being behind the assassination of Iranian nuclear scientists and of trying to damage its program in other ways.

Earlier this month Israel's prime minister, Benjamin Netanyahu, said Israel was ready to act alone to stop Iran making a nuclear bomb.

And during a visit to the UN in the United States last month, Iranian president Hassan Rouhani held a phone call with US president Barack Obama.

It was the first official direct communication between the two countries' leaders in more than 30 years.

AFP/Reuters