“Those who are intimidated by the enemy’s demands will retreat step by step and finally surrender. But nobody has the right to do so, and the nation will not allow it,” the all-powerful leader said in a meeting with members of Parliament. Khamenei’s comments come amid mounting US allegations that Iran has a secret nuclear weapons porgram and is attempting to undermine the US presence in Iraq through support of hard-line Shiite groups.

Furthermore, Iran has been accused of sheltering top Al-Qaeda members Washington accuses of links to suicide bombings in Riyadh that killed 34 people on May 12. The string of allegations from senior US officials come amid reports that the Bush administration may embark on a new policy of trying to topple the Islamic regime, while stopping short of a full-scale military attack. The allegations have already torpedoed tentative steps to resume dialogue between Tehran and Washington, which cut diplomatic relations after Iran’s 1979 revolution.

Khamenei said this psychological campaign was already under way, accusing the United States of using its “media empire to spread the virus of fear and anxiety”. It “will not be satisfied until Iran’s officials and people cast aside their values,” he said. The supreme leader has also come under pressure from reformist MPs allied to President Mohammad Khatami, who argue that the stalling of reforms by powerful hard-line institutions seen as loyal to Khamenei was putting the survival of the regime at risk.

But Khamenei responded by asserting that “criticizing and protesting is no problem ... but one should be careful that these debates and differences in viewpoints do not end in hostilities and confrontations that benefit the enemy.” Khamenei was one of a string of top Iranian officials lining up to condemn Washington, including Khatami.

In a speech opening a three-day meeting of Organization of Islamic Conference (OIC) foreign ministers, Khatami implicitly referred to the danger of Al-Qaeda, but also to the conduct of the United States in its war against terrorism. “It is incumbent on us, in the name of Islam, to keep a distance from these two frightening faces,” Khatami said.

For his part, Foreign Ministry spokesman Hamid Reza Asefi said it was Iran that was “the first victim of Al-Qaeda, and we have been fighting them from the very beginning.” When asked to elaborate on suspected Al-Qaeda members Iran says are detained here, Asefi would only say that interrogations were ongoing.

“There are some in custody. I am not in a position to say who they are. We have to clarify their identity,” Asefi said, adding that Iran was in “close contact with friendly countries” over the detainees, including Saudi Arabia.