Israeli Prime Minister Ehud Olmert's spokeswoman Miri Eisin told Xinhua that the report by British newspaper The Sunday Times was "totally fabricated" and it did not single out any specific information sources it mentioned.

Citing alleged several Israel Defense Forces (IDF) sources, The Sunday Times said two Israel Air Force (IAF) squadrons had been training to blow up an enrichment plant in Natanz using low-yield nuclear "bunker busters."

Meanwhile, two other sites, a heavy water plant at Arak and a uranium conversion plant at Isfahan, would be targeted with conventional bombs, it added.

The IDF had no comments on the report so far.

In the wake of the report, Iranian Foreign Ministry spokesman Mohammad-Ali Hosseini said any measure against Iran would not remain unanswered and "the attacker would quickly regret the action", according to Iran's official IRNA news agency.

During an interview with Xinhua last Friday, Olmert downplayed the possibility of an Israeli military action against Iran.

"I hope that the day will not come. I hope very much that the diplomatic measures and the economic sanctions will be effective,"said Olmert, adding "if we take necessary diplomatic measures together with the economic sanctions ... the outcome will be positive."

The UN Security Council passed a resolution on Dec. 23, 2006, demanding Iran suspend all enrichment-related and reprocessing activities, while imposing a nuclear-related trade ban on Iran.

However, Tehran vowed to continue its nuclear program despite the resolution, calling its nuclear program a peaceful effort to develop energy.