A report by the U.N.'s atomic watchdog agency released Thursday sets the stage for renewed debate in the Security Council over whether Iran should face tougher sanctions because of its nuclear program.
The United States, France and Britain said the report shows that Iran's nuclear technology was advancing while the agency's knowledge and oversight of it was diminishing. And the three pushed for more penalties against Tehran.
"I don't like to see this issue being discussed here [in the Security Council]," said China's ambassador to the U.N., Wang Guangya. "We already have two resolutions on the sanctions, and what do we have?"
U.S. Ambassador Zalmay Khalilzad said the council should continue with diplomacy, but also move forward with a resolution imposing a third round of sanctions.
"For diplomacy to succeed, it needs widely supported, broad and biting sanctions to affect the calculations of the regime in Iran," he said. "I don't believe the Chinese would want to take responsibility for the failure of diplomacy by not cooperating with the effort at additional sanctions."
Security Council members agreed in September to hold off on tougher penalties against Iran for its refusal to suspend uranium enrichment, hoping to give Mohamed ElBaradei, director-general of the United Nations' International Atomic Energy Agency, time to assess whether Tehran is trying to use its nuclear technology or materials to produce weapons.
But without a clear-cut judgment about Iran's intentions, the council finds itself no less divided than it has been over the last four years.
The much-anticipated IAEA report says Iran has been mostly forthcoming about the history of its nuclear program, but has left many questions about its current activities unanswered.
It also notes that Iran is operating 3,000 gas centrifuges -- 10 times the number it had nearly a year ago when the council first demanded that Tehran suspend uranium enrichment. The centrifuges enrich uranium so it can be used to generate electricity or, at much higher levels, in a weapon. IAEA inspectors said the centrifuges were operating well below their potential, implying either that they were not working smoothly, or that Iran was intentionally showing restraint.
The report says Iran had tested a new version of the centrifuge without nuclear material, but did not allow IAEA inspectors to visit the site.
That lack of access means that "the agency's knowledge about Iran's current nuclear program is diminishing," ElBaradei said.
But ElBaradei also noted that Iran had made "substantial progress" in revealing the extent of its past procurement efforts.
Tehran has answered questions about how it acquired black-market nuclear technology during the two decades it developed its atomic program in secret.
The report is slightly more critical than expected, but is a disappointment for diplomats who hoped that it would show either marked improvement in Iran's cooperation, or demonstrate a degree of recalcitrance that would persuade China and Russia to join Britain, France and the U.S. in their drive for further penalties. The countries hold the five permanent seats on the Security Council.
"The IAEA showed that they can't even resolve questions about Iran's past, that knowledge of present activities is diminishing, and they cannot clarify Iran's future intentions because of the lack of cooperation," said Britain's ambassador to the U.N., John Sawers. "That is really worrying."
In Iran, chief nuclear negotiator Saeed Jalili said the report showed that Iran had been transparent, but hinted that Tehran would halt its cooperation if more sanctions were imposed. "There should be no reasonable justification for further resolutions," he told reporters in Tehran.
Jalili also criticized the U.S. for calling for another round of penalties even before the report came out.
Last week, Iran handed over a blueprint showing how to shape uranium metal into hemispheres for a nuclear warhead, the report said.
IAEA inspectors had discovered the document in 2005. They had been permitted to read it then, but not take it out of the country.
Iranian officials said the blueprint had been provided unsolicited by Pakistani scientist Abdul Qadeer Khan, known as the father of Pakistan's atomic bomb, and that they didn't try to manufacture a weapon from it.
Handing over the document was one of ElBaradei's demands under a "plan of work" arrived at in the summer with Iran. He has said he hoped to finish an inquiry into a list of questions posed to the Iranians by the end of the year. Reaching that goal appears unlikely: The agency has resolved only one issue, about past plutonium experiments.
On Thursday, Jalili said Tehran had provided all necessary information about the centrifuges and that the dossier should be closed. The report does not say that.
"It is not closed," said a diplomat close to the IAEA who is not authorized to comment on the record and therefore spoke on condition of anonymity. "It is a long and complex process, and is not complete."
The U.S. and others have criticized ElBaradei's work plan, saying it allows Iran to stall and keep the focus on the past instead of addressing questions about the present.
"In a way, ElBaradei fell into a trap of his own making," said David Albright, head of the nonpartisan Institute for Science and International Security. Albright said that even if Iran answered all the questions about the past, the IAEA would still not know whether Tehran was now trying to develop nuclear weapons.
But ElBaradei's team believes that his strategy is bringing results.
"We have been trying to get these issues resolved for five years, and now suddenly there is movement," said the diplomat close to the IAEA. "That's a step in confidence building and also an effort to clarify the very issues that triggered the call for suspension and sanctions in the first place."
Special correspondent Ramin Mostaghim in Tehran contributed to this report.