Vienna, Austria ? Raising doubts about its commitment to dispel international distrust, Iran is producing significant quantities of a gas that can be used to make nuclear arms just days before it must stop all work related to uranium enrichment, diplomats said Friday.

Iran recently started producing uranium hexafluoride at its gas-processing facilities in the central city of Isfahan, the diplomats told The Associated Press.

When introduced into centrifuges and spun, the substance can be enriched to varying degrees. Low-grade enriched uranium is used in nuclear power plants. Highly enriched uranium forms the core of nuclear warheads.

While Iran says it is only interested in enrichment to generate power, the United States and its allies accuse Tehran of wanting the technology to make weapons-grade uranium.

In the latest accusation, Secretary of State Colin Powell said Wednesday he had seen intelligence to confirm claims by an Iranian dissident group that Tehran was secretly running a program intended to produce nuclear weapons by next year.

Iranian Foreign Minister spokesman Hamid Reza Asefi dismissed that allegation Friday.

“There is no place for weapons of mass destruction in Iran’s defense doctrine,” he said, according to the official Islamic Republic News Agency.

Asefi suggested that U.S. officials “reconsider their intelligence sources.”

Members of a key Iranian resistance group march up Constitution Avenue on Capitol Hill in Washington, D.C., to protest Iran's nuclear weapons drive. Thousands of demonstrators protested the European Union's dealings with the current Iranian government and their nuclear program, rallying ahead of the Nov. 25 meeting of the International Atomic Energy Agency.

Iran last week agreed to suspend uranium enrichment and all linked activities in a deal worked out with Britain, France, Germany and the European Union. The deal, which goes into force Monday, prohibits Iran from all uranium gas-processing activities, as well as other programs linked to enrichment.

A senior EU diplomat said Iran’s decision to carry out uranium processing right up to the freeze deadline disappointed the Europeans and cast doubt on Tehran’s goodwill — even if it did not violate the letter of the agreement.