Iran said on Tuesday that the West had no serious proof it was developing nuclear weapons, ahead of a report by the UN atomic watchdog that is expected to provide new evidence against Tehran.

"There is no serious proof that Iran is going to create a nuclear warhead," Foreign Minister Ali Akbar Salehi said, responding to a question about the International Atomic Energy Agency report during a visit to neighbouring Armenia.

"The West and the United States are exerting pressure on Iran without serious arguments and proof," he said.

The IAEA report expected this week has been raised as a potential trigger for an Israeli attack on Iran's nuclear facilities.

Diplomats have said that the report will focus on the Islamic republic's alleged efforts to put fissile material in a warhead and on developing missiles.

Previous IAEA assessments have centred on Iran's efforts to produce fissile material -- uranium and plutonium -- which can be put to peaceful uses such as power generation or be used to make a nuclear bomb.

Iranian President Mahmoud Ahmedinejad on Monday accused Israel and the United States of seeking backing for a military strike.

"Now Israel and the West, particularly America, fear Iran's capabilities and role... Therefore they are trying to gather international support for a military operation to stop (Iran's) role," Ahmedinejad said.

Israeli President Shimon Peres warned on Sunday that a strike against Iran was becoming more likely.

"The possibility of a military attack against Iran is now closer to being applied than the application of a diplomatic option," Peres said.

Salehi repeated Tehran's position that its nuclear programme was for peaceful purposes only.

"We have repeatedly stated that we are not going to create nuclear weapons," he said. "Our position has always been that we will never use our nuclear programme for purposes other than peaceful ones."

Iranian officials, who diplomats say have already seen the IAEA report, have dismissed it as being based on false information.

But the White House said on Monday that it expected the UN nuclear watchdog to echo its concerns, and as is customary refused to rule out the use of military force.

"We certainly expect it to echo and reinforce what we've been saying about Iran's behaviour and its failure to live up to its international obligations," said White House spokesman Jay Carney.

Germany's foreign ministry on Monday called for "greater political and diplomatic pressure" on Iran to comply with international commitments on its nuclear programme.

But Russia's Foreign Minister Sergei Lavrov warned against any military action, arguing that it would be "fraught with unpredictable consequences".

Iran has so far refused to freeze its uranium enrichment activities despite being hit with several UN sets of sanctions.