Reporting from Beirut — Iran's move on Tuesday to produce higher-grade uranium for a medical reactor prompted widespread international condemnation and an uncharacteristically harsh response from Russia, whose support is key to U.S.-led efforts to impose tough new sanctions against the Islamic Republic.
But the response from China, which like Russia wields a U.N. Security Council veto and maintains robust economic ties with Iran, was far more muted, suggesting a tough road ahead for the Obama administration and Western allies seeking to put pressure on Tehran.
Iranians in lab coats at the Natanz facility cried "God is great!" as they transferred uranium from one capsule to another, presumably to begin the enrichment process, state television showed.
But it was unclear from its statements whether Iran had actually started producing higher-grade uranium or had only begun testing the process.
Tehran has said it will turn some of its uranium, currently enriched to 3.5% purity and suitable for generating electricity, into material of 20% purity necessary to power an ailing Tehran medical reactor. The West fears that Iran's goal is to eventually produce high-grade uranium for weapons.
The Obama administration quickly condemned Iran's move.
"It's provocative, and it deepens our concerns about what the Iran leadership's intentions are," said Philip J. Crowley, the chief State Department spokesman.
President Obama said the administration and five other world powers are "moving along fairly quickly" to develop new sanctions on Iran to persuade it to abandon its nuclear ambitions.
The U.S. criticism of Iran's latest move was echoed by Russian lawmakers, commentators and ranking officials.
"Iran says it doesn't want to have nuclear weapons. But its actions, including its decision to enrich uranium to 20%, have raised doubts among other nations, and these doubts are quite well founded," Nikolai Patrushev, the nation's security chief, told Russian news agencies.
Russian Foreign Ministry spokesman Andrei Nesterenko was quoted on the department website as declaring: "Iran's decision . . . increases doubts in the sincerity of Iran's intentions to ease, through joint efforts, the existing concerns of the international community with regard to the Iranian nuclear program."
But Beijing, which has balked at even harshly rebuking Iran, continued to call for more diplomacy.
"China hopes all relevant parties will step up diplomatic efforts and make progress in dialogue and negotiations," Foreign Ministry spokesman Ma Zhaoxu said Tuesday during a regular briefing, the official New China News Agency reported.
Low-enriched uranium, which Iran already has, can power electricity-producing reactors, whereas uranium enriched at levels of 60% or higher can be used to make a nuclear weapon.
Iran's nuclear chief, Ali Akbar Salehi, told state-run news media that inspectors from the United Nations' International Atomic Energy Agency will observe the process of further refining the fuel, while Iranian diplomats continue to negotiate with the West over a U.N.-backed proposal for Iran to send its low-grade material to Russia in exchange for fuel plates made in France.
"The enrichment of uranium up to 20% does not mean the doors are closed to interaction and negotiations for fuel exchange," Salehi said, according to the official Islamic Republic News Agency. "In case our adversary parties in the negotiations show wisdom and stop killing time, the Islamic Republic will be ready to go ahead with interaction."
Salehi told the semiofficial Iranian Students News Agency that Iran plans to devote 164 centrifuges to further refining some of its 4,000-pound supply of low-enriched uranium into fuel for the medical reactor and produce as much as 11 pounds of 20% enriched uranium a month, which is more than the 4 pounds a month needed to produce isotopes for cancer treatment and diagnosis at the medical reactor.
Salehi said a uranium conversion plant in Esfahan can convert the 20% enriched uranium into fuel plates for the reactor, which is due to run out of fuel this year.
"In the past seven months, any time Iran mentioned it could meet its fuel needs, Western nuclear experts and politicians questioned Iran's capability to produce fuel plates," state television quoted Salehi as saying. "But we have mastered the sophisticated technology of producing fuel plates."
Times staff writers Paul Richter in Washington and Megan K. Stack in Moscow contributed to this report.