President George Bush dismissed claims that his administration was planning a pre-emptive military strike against Iran as "wild speculation" today.

Mr Bush was reacting to two articles — one in The Washington Post on Sunday and another in The New Yorker magazine today — claiming that hawkish officials in the Pentagon and the White House were recommending a forceful change of regime in Tehran.

In The New Yorker, Seymour Hersh, the Pulitzer-prize winning investigative reporter, wrote that military planners had drawn up a list of targets for nuclear strikes to eliminate the threat of Iran's rumoured atomic weapons programme.

Hersh claimed that Mr Bush has become convinced that he has a historical mission to remove President Mahmoud Ahmadinejad, the hardline leader of Iran who has called for Israel to be "wiped off the map".

In a speech to John Hopkins University, Mr Bush paused to comment on the reports which have consumed America's media: "By the way I read the articles in the newspapers and it was just wild speculation... What you're reading is wild speculation."

The President insisted that his promise to prevent Iran from obtaining nuclear weapons — made in his National Security Strategy published earlier this year — "doesn’t mean force necessarily. In this case it means diplomacy."

The press reports formed part of a flurry of exchanges between Tehran, Washington and Brussels today as five inspectors from the International Atomic Energy Agency (IAEA) continued to examine nuclear research facilities in Iran.

The IAEA will report its findings to the UN Security Council on April 28, when the permanent members will decide whether or not to impose economic sanctions on Iran for disguising a nuclear weapons programme as a peaceful attempt to secure a new source of energy.

Javier Solana, the EU foreign policy chief, said today that trade and travel restrictions for Iranian officials were being considered but that military force was not on the table. "Any military action is definitely out of the question for us," he said.

But President Ahmadinejad accused the West of attempting to sow disharmony in Iran. One of the claims in Hersh's article centred on US attempts to win support from dissidents inside the country. In recent months, the Bush administration has set up a 24-hour cable channel to broadcast into Iran.

Speaking to thousands of people in Mashad, a provincial capital in northeastern Iran, Mr Ahmadinejad said: "Our enemies know that they can’t cause a minute’s pause in our nation’s motion forward. Unfortunately today some bullying powers are unable to give up their bullying nature. The future will prove that our path was a right way."

"They have pinned their hope to create differences among our nation," said Mr Ahmadinejad, who promised "good nuclear news" for Iran in the coming days but did not elaborate.

Ali Larijani, the secretary of Iran’s supreme National Security Council and chief nuclear negotiator, advised America against the military option: "If the US commits such a mistake, it would receive a convenient answer," he was quoted as saying by IRNA, the state news agency.

The American news reports came after weeks of intense discussion in Washington about a possible change of stance towards Iran.

At the end of March, Joseph Cirincione, a director for non-proliferation at the Carnegie Endowment for International Peace and one of America's leading Iran experts, caused controversy saying that he believed that statements from the White House echoed those made in the run-up to the invasion of Iraq.

"For months, I have told interviewers that no senior political or military official was seriously considering a military attack on Iran. In the last few weeks, I have changed my view," Mr Cirincione wrote on the website of Foreign Policy magazine.

"In part, this shift was triggered by colleagues with close ties to the Pentagon and the executive branch who have convinced me that some senior officials have already made up their minds: They want to hit Iran," he wrote.

Jack Straw, rubbished reports of a move towards a military strike as "nuts". He added: "I’m as certain as I can be sitting here that neither would the United States."

"There is no smoking gun, there is no casus belli [just cause for war]. We can’t be certain about Iran’s intentions and that is, therefore, not a basis on which anybody would gain authority to go for military action," he told the BBC.

Peter Brookes, Deputy Assistant Secretary of Defence in the first Bush Administration, also played down the significance of the recent stories, saying that plans for military strikes against Iran had existed since the late 1970s and the Iranian Revolution.

"The fact of the matter is: we have war plans, every country does," he told Times Online. "And they are updated on a regular basis... You can't just flip the switch and see what happens."

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