The allegation comes only three days after an agreement was struck between Iran and three European nations to curb Iran's ability to make nuclear weapons. The pact, which goes into effect Monday, stipulates that Iran suspend its program to enrich uranium. Iran has strongly denied it is trying to build nuclear weapons, but enriched urnanium can be used to make nuclear bombs as well as fuel for atomic reactors.

Mr. Powell gave no details of the intelligence on Iran's missile program. But independent arms control experts say there are indications, at least, of some changes in missile development in Iran, particularly of the Shabab-3 missile.

The missile is believed to be a derivative of a missile series called the No-Dong, which analysts say Tehran acquired from North Korea. The Shebab-3, which has a range of up to 1,500 kilometers, has been tested several times this year, most recently on October 20.

Doug Richardson, editor of Jane's Missiles and Rockets, says he noticed a different configuration of the missile when he saw the footage of the test. He says there appears to be some effort to lighten the payload, a change consistent with trying to retrofit a missile for a nuclear warhead. "The payload that this re-entry vehicle could carry, I should imagine, was much lighter than that of the original Shahab payload. And that makes me wonder if they're looking at a weapon of mass destruction," he said. "But certainly when I saw that smaller warhead my first reaction was, I wonder if this is intended for a WMD payload."

Henry Sokolski, executive director of the Nonproliferation Policy Education Center, says there is an inconsistency in Iran's agreeing to curb its nuclear program while pursuing missile warhead technology. "You can't really argue on the one hand that you have a solution to Iran possibly getting nuclear weapons, and then argue, but of course , they're working to develop delivery systems for them," he said. "So it does seem as though the secretary (of state) is throwing a bit of cold water on the idea that we can give Iran a diplomatic hug, if you will, and get them to change their minds about a program that appears to be active. I mean, there's no other way to describe it."

The governing board of the International Atomic Energy Agency, or IAEA is to meet next week to discuss Iran's nuclear program. The United States would like the U.N. Security Council to impose punitive measures on Iran for its alleged violations of the Nuclear Nonproliferation Treaty. U.S. State Department spokesman Adam Ereli says that while missile system development is not a subject for the IAEA or Security Council to discuss, it is still indicative of what the United States says are Iran's nuclear weapons ambitions.

"That's not a subject of or a matter for the IAEA It's not a subject of discussion at the IAEA board of governors. That's another piece of the puzzle," he said. "It deals with not necessarily the development of weapons of mass destruction but the development of delivery systems. Again, that has been a concern that we have voiced very consistently."