Tehran has accused saboteurs of attempting to manually disrupt the key Arak atomic plant, as world powers gathered in Vienna to settle a decade-old dispute over Iran's nuclear activities.
Pumps at the Arak reactor, seen by the West as a potential source of plutonium for nuclear bombs, were tampered with in a failed attempt to undermine the country's nuclear programme, a senior official said on Monday.
Asghar Zarean, an official with the Atomic Energy Organisation of Iran, said the incident was one of several such attacks foiled over the past few months, the official IRNA news agency reported.
He did not name the targets of the other attacks or who might have been behind them. Iran has previously accused its Western and Israeli foes of seeking to sabotage its nuclear programme, which Tehran says is peaceful but the United States and its allies fear may be aimed at developing a nuclear weapons capability.
Iran's nuclear programme has previously been the target of computer virus attacks suspected to have originated with Western or Israeli intelligence services. Iran has also accused its enemies of assassinating Iranian nuclear scientists.
But the events described on Monday are believed to be the first sabotage suspicions made public by Iran since a major thaw in ties with the West. That thaw came after a relative moderate, Hassan Rowhani, was elected president last June on a platform to ease Tehran's isolation.
"Intelligence inspections of the nuclear facilities indicated that some pumps ... of Arak's IR-40 project had been mechanically manipulated in an effort to disrupt the routine work of the power plant," Zarean said.
A report by the UN nuclear watchdog in November last year said several major components had yet to be installed at the plant, including reactor cooling pumps. It was not immediately clear whether Zarean was referring to another type of pump.
The fate of Arak was a big sticking point in talks between Iran and six world powers last year that led to a landmark interim agreement to curb Iran's nuclear programme in exchange for an easing of sanctions.
Under the accord that took effect on January 20, Iran pledged not to install any additional reactor components or produce fuel for the plant during the six-month duration of the deal.
The powers - the United States, France, Germany, Britain, China and Russia - and Iran were due to meet again in Vienna yesterday to try to build on the interim accord and reach a final settlement by late July of the dispute over the Islamic Republic's atomic activities.