Updated

Iranian president Mahmoud Ahmadinejad said Tuesday that the Islamic republic did not need a nuclear bomb to confront the U.S., in comments made ahead of the release of a new report from the U.N. atomic watchdog.

"If America wants to confront the Iranian nation, it will certainly regret the Iranian nation's response," Ahmadinejad was quoted as saying by the IRNA news agency. "They are saying that Iran is seeking the atomic bomb. But they should know ... we do not need a bomb ... Rather we will act thoughtfully and with logic. History has shown that anyone acting against the Iranian nation regrets it."

Earlier Tuesday, Iran's foreign minister Ali Akbar Salehi said during a visit to Armenia that the U.S. and other Western nations have no proof that Iran is developing nuclear weapons.

"There is no serious proof that Iran is going to create a nuclear warhead," Salehi was quoted as saying by AFP during a visit to Armenia. "The West and the United States are exerting pressure on Iran without serious arguments and proof. We have repeatedly stated that we are not going to create nuclear weapons."

The U.N.'s International Atomic Energy Agency (IAEA) is set to release a report Wednesday detailing new evidence of Tehran's drive to make nuclear weapons.

The report points to a former Soviet weapons scientist who allegedly tutored Iranians to overcome key technical hurdles, The Washington Post reported.

Iran also was helped over the threshold of nuclear capability via crucial technology linked to experts in Pakistan and North Korea.

Chinese foreign ministry spokesman Hong Lei told reporters Tuesday that Tehran should "show flexibility and sincerity and engage in serious cooperation with the agency" while urging the IAEA to be "just and objective."

"China is against the proliferation of nuclear weapons and opposes the development of nuclear weapons by any country in the Middle East region. It is imperative to prevent new turbulence in the Middle East security situation," Hong said.

The upcoming IAEA report is likely to further stoke simmering global tensions over Iran, with Israel considering the possibility of a preemptive strike and the UK said to be making military preparations to support any U.S.-led action against the Islamic nation.

On Monday, Ahmadinejad said the U.S. and Israel feared Tehran's atomic program but insisted that it was for peaceful purposes only.