By DOUGLAS JEHL
WASHINGTON - An Iranian opposition group says it has new evidence that Iran is producing enriched uranium at a covert Defense Ministry facility in Tehran that has not been disclosed to United Nations inspectors.
The group, the National Council for Resistance in Iran, is planning to announce its finding in Paris on Wednesday. The group says that inspection of the site would demonstrate that Iran is secretly trying to produce nuclear weapons even while promising to freeze a critical part of its declared nuclear program, which it maintains is intended purely for civilian purposes.
A senior official of the group, Muhammad Mohaddessin, said in a telephone interview late on Tuesday that the group had shared the new information "very recently'' with the International Atomic Energy Agency. But he and other officials of the group said it had not discussed the matter with the United States government, and its claims could not be verified.
Iran's mission to the United Nations did not return messages seeking comment on the assertion.
The group, based in Paris, is the political arm of the People's Mujahedeen, which is listed by the United States government as a terrorist organization because of its involvement in attacks on Americans in the 1970's. But the group also has a successful track record in gathering intelligence on Iran, and was the first, in 2002, to disclose the existence of what was then the secret Iranian nuclear site at Natanz.
United Nations inspectors "should not be fooled or deceived by the Iranian regime,'' Mr. Mohaddessin said.
A spokesman in Washington for the National Council for Resistance in Iran provided a seven-page summary of the assertion to The New York Times.
It says that the previously undisclosed site, in northeastern Tehran, covers 60 acres and houses biological and chemical warfare projects as well as nuclear activity. It says that the site, known as the Modern Defensive Readiness and Technology Center, now houses operations previously carried out at another Defense Ministry site in Tehran that was destroyed by the Iranian government this year before international inspectors could visit it.
The assertion by the opposition group is surfacing in a week in which France, Britain and Germany announced a formal agreement with Iran committing the country to freeze a critical part of its nuclear program in exchange for an array of possible rewards.
As part of the pact with the Europeans, the International Atomic Energy Agency said Iran had promised to suspend its uranium enrichment program starting a week from now. But the agency said it could not rule out the possibility that Iran was conducting covert activities.
"All the declared nuclear material in Iran has been accounted for, and therefore such material is not diverted to prohibited activities," the agency said in a report, referring to possible Iran nuclear weapons activity. "The agency is, however, not in a position to conclude that there are no undeclared nuclear materials or activities in Iran."
The United States and European countries have argued that Iran's nuclear program is intended to produce weapons. Iran's leadership has insisted that is not engaged in a nuclear weapons program but has the sovereign right to enrich uranium.
Officials of the opposition group said they believed that the Iranian Defense Ministry and Revolutionary Guards Corps were pursuing their program in secret and had not told Iran's atomic energy agency of the existence of the facility in Tehran.