VIENNA, Austria — Iran is moving closer to the point of being able to arm a warhead with a nuclear core even if it insists its atomic activities are peaceful, the European Union warned today.

In comments prepared for the International Atomic Energy Agency’s 35 board members, the E.U. also asserted that Iran appeared to have had a past nuclear arms program despite denials from Tehran.

The statement was made available to reporters as the agency’s board turned its attention today to Iran’s nuclear defiance. The group is concerned about Tehran’s refusal to freeze uranium enrichment despite sets of three U.N. Security Council sanctions and its stonewalling of IAEA attempts to follow up on intelligence suggesting it was developing a nuclear arms program up until several years ago.

Iran insists its nuclear activities are geared only toward generating power. But Israel says the Islamic Republic could have enough nuclear material to make its first bomb within a year. America estimates that Iran is at least two years away from that stage, and some experts say Iran could reach that stage in as little as 6 months through uranium enrichment.

An IAEA report drawn up for the International Atomic Energy Agency’s board meeting says that Iran has increased the number of centrifuges used to process uranium to nearly 4,000 from 3,000 just a few months ago.

But David Albright, whose Washington-based Institute for Science and International Security closely tracks suspected secret proliferators, has also been able to extrapolate other information from the report that is less obvious but of at least equal concern.

Iran, he says, has managed to iron out most of the bugs in the intensely complicated process of enrichment that often saw the centrifuges breaking down. The machines, he says “now appear to be running at approximately 85% of their stated target capacity, a significant increase over previous rates.”

That means, he says, they can produce more enriched uranium faster. And while the IAEA says the machines have spewed out only low-enriched material suitable solely for nuclear fuel, producing enough of that can make it easy to “break out” quickly by reprocessing it to weapons- grade uranium suitable for the fissile core of a warhead.

To date, Iran has produced nearly 1,000 pounds of low-enriched uranium, said the report — close to what Mr. Albright says is the 1,500-pound minimum needed to produce the 45-60 pounds needed for a simple nuclear bomb under optimal conditions.

And with Iran’s centrifuges running ever more smoothly, it “is progressing toward this capability and can be expected to reach it in six months to two years,” Mr. Albright said.

Touching on such fears, the statement by the 27-nation EU said Iran’s defiance of Security Council demands on enrichment is troubling “because it brings us closer to the moment where Iran will have fissile materials for a weapon.”

It also cast serious doubt on Iranian assertions that it never embarked on studies geared toward making nuclear weapons.

While the evidence “remains to be verified, the IAEA’s exhaustive and detailed” information “leads one to think that the Iran has methodically pursued a program aimed at acquiring the nuclear bomb,” the E.U. statement said.

In a statement, Iran’s mission to the IAEA again denied wrongdoing and suggested the pressure on Tehran was part of an American witch hunt.

The Islamic Republic “has repeatedly declared that there is not and has not been any undeclared nuclear activities and material in Iran,” it said, denouncing the “fabricated and baseless allegations … produced by the United States.”

An IAEA report circulated to the board members Monday faulted Iran for blocking efforts to further investigate the alleged weapons program.

Part of the report spoke of what appeared to be drawings and calculations by Iranian engineers on reconfiguring its Shahab-3 missile to be able to carry a nuclear payload. Iranian officials say the missile has a range of 1,250 miles — 2,000 kilometers — enabling a strike on Israel and most of the Middle East.

Urging Iran to cooperate with both the IAEA and the Security Council, the E.U. statement said: “It is not for Iran to contest the authority of the Security Council or of this agency,” in their attempts to probe Tehran’s past and get it to suspend uranium enrichment.