Tehran, Iran ? Iran said Friday it would continue to limit the operations of the U.N. nuclear watchdog agency, setting the stage for a confrontation with the United States.

The International Atomic Energy Agency has said it expected Iran “to grant the agency all access deemed necessary” to defuse suspicions Tehran is operating a clandestine nuclear weapons program.

President Bush, who has called Iran and North Korea members of an axis of evil, has said he and other world leaders will not tolerate nuclear weapons in Iran.

In London, a senior U.S. official said that while military action against Iran to stop it developing nuclear weapons was far from the thoughts of Washington, it remained a last resort.

John Bolton, undersecretary of state for arms control and international security, insisted Iran could not be allowed to develop a weapons capability that could destabilize the whole region.

Asked whether the Bush administration reserved the right to take military action against Iran, he said: “The president has repeatedly said that all options are on the table. But that is not only not our preference, it is far, far from our minds.”

Iran’s state television said the head of Iran’s Atomic Energy Organization, Gholamreza Aghazadeh, would not permit environmental sampling at “some locations.” It did not name the locations. The refusal indicated a hardening of attitude toward the U.N. nuclear watchdog group.