WASHINGTON — In their last report before the United Nations Security Council votes on sanctions against Iran, international nuclear inspectors declared Monday that Iran has now produced a stockpile of nuclear fuel that experts say would be enough, with further enrichment, to make two nuclear weapons.
The report, by the International Atomic Energy Agency, a branch of the United Nations, appears likely to bolster the Obama administration’s case for a fourth round of economic sanctions against Iran and further diminish its interest in a deal, recently revived by Turkey and Brazil, in which Iran would send a portion of its nuclear stockpile out of the country.
When Iran tentatively agreed eight months ago to ship some of its nuclear material out of the country, the White House said the deal would temporarily deprive Iran of enough fuel to make even a single weapon.
But Iran delayed for months, and the figures contained in the inspectors’ report on Monday indicated that even if Iran now shipped the agreed-upon amount of nuclear material out of the country, it would retain enough for a single weapon, undercutting the American rationale for the deal.
The toughly worded report says that Iran has expanded work at one of its nuclear sites. It also describes, step by step, how inspectors have been denied access to a series of facilities, and how Iran has refused to answer inspectors’ questions on a variety of activities, including what the agency called the “possible existence” of “activities related to the development of a nuclear payload for a missile.”
A spokesman for the White House, Michael Hammer, said in a statement on Monday that the report “clearly shows Iran’s continued failure to comply with its international obligations and its sustained lack of cooperation with the I.A.E.A.” He said the report “underscores that Iran has refused to take any of the steps required of it” by the Security Council or the I.A.E.A.’s board of governors, “which are necessary to enable constructive negotiations on the future of its nuclear program.”
Iran, which insists that its nuclear program is for peaceful purposes, has said that it has conducted no work on weapons, and argues that the evidence of work on warheads is forged.
Iran’s nuclear progress had been expected to be a central subject at a meeting scheduled for Tuesday at the White House between President Obama and Prime Minister Benjamin Netanyahu of Israel. Mr. Netanyahu canceled the visit after a deadly raid by Israeli commandos on ships carrying supplies to Gaza.
But the I.A.E.A. report left hanging the question of whether Israel would ratchet up the pressure on Washington and its allies to show that they can deal with the threat of a nuclear-armed Iran diplomatically. Israeli officials have hinted, but never explicitly threatened, that they would take military action if diplomacy fails and Iran is close to weapons capability.
Administration officials have argued that the combination of the sanctions they expect to come out of the Security Council, along with other sanctions imposed by the United States and its European allies, may change Iran’s calculus. But many inside and outside the administration are highly skeptical.
It has been four years since the Security Council first demanded that Iran cease all enrichment of uranium, citing its efforts to hide its activities and deceive inspectors. The country has openly defied those resolutions, telling inspectors that those demands — along with calls to allow inspectors to visit a series of facilities that could be useful in energy or weapons production — had been “issued illegally and have no legal basis.”
The inspectors reported Monday that Iran has now produced over 5,300 pounds of low-enriched uranium, all of which would have to undergo further enrichment before it could be converted to bomb fuel.
The inspectors reported that Iran had expanded work at its sprawling Natanz site in the desert, where it is raising the level of uranium enrichment up to 20 percent — the level needed for the Tehran Research Reactor, which produces medical isotopes for cancer patients. But it is unclear why Iran is making that investment if it plans to obtain the fuel for the reactor from abroad, as it would under its new agreement with Turkey and Brazil.
Until recently, all of Iran’s uranium had been enriched to only 4 percent, the level needed to run nuclear power reactors. While increasing that to 20 percent purity does not allow Iran to build a weapon, it gets the country closer to that goal. The inspectors reported that Iran had installed a second group of centrifuges — machines that spin incredibly fast to enrich, or purify, uranium for use in bombs or reactors — which could improve its production of the 20 percent fuel.
The inspectors also noted that the agency had finally succeeded in setting up a good monitoring system for the 20 percent work after a rocky start in February, when Iran began raising the enrichment levels. “A new safeguards approach is now being implemented,” the report said.
But the report called the equipment upgrades and the continuing enrichment “contrary to the relevant resolutions of the I.A.E.A.’s Board of Governors and the Security Council.” Both have called on Iran to cease its uranium enrichment because of outstanding questions about Tehran’s intentions. The sanctions, if passed, are intended to compel Iran to comply with that demand by the Security Council.
Last fall, President Obama, along with the leaders of Britain and France, denounced Iran for secretly building a second enrichment plant near the city of Qum, without alerting inspectors until just before the three leaders’ countries announced they had discovered the facility. But curiously, the report suggested that now, with its existence revealed, Iran might be losing interest in it. The report said that Iran had installed no centrifuges in the half-built enrichment facility, which is located inside a mountain near a military base.
Iran has sought to locate many of its nuclear facilities in underground sites so as to lessen their vulnerability to aerial attacks. In the new report, the inspectors said that the Iranians disclosed that a new analytical laboratory planned for construction amid a warren of tunnels at Isfahan “would have the same functions as the existing” unprotected laboratory there.
The report quoted an Iranian letter as saying the second, underground laboratory was needed “to meet security measures.”