UN: Iran has diluted sensitive nuclear material

Iran had more than 200 kilograms of 20-percent-enriched uranium when the preliminary agreement was reached. That's nearly enough for one warhead.

A report from the U.N.'s International Atomic Energy Agency said that all of it has now been converted or diluted, according to The Associated Press. The report said Iran was observing all its other commitments as well.

That stockpile was closely watched by the West because 20 percent enrichment represents a relatively short technical step from that required for nuclear weapons. Iran denies wanting such arms and says it is refining uranium only to fuel nuclear power plants or research reactors.

Tehran is keen to seal a deal that would end nuclear-related sanctions on its economy but is resisting a U.S.-led drive to put stiff, long-term constraints on atomic activities that have both peaceful and weapons-related applications.

The main dispute is over uranium enrichment, which is necessary to produce reactor fuel and the fissile core of nuclear warheads.

Up to last week, Tehran had demanded that it be allowed to expand its enrichment program over the next eight years to a level that would need about 190,000 current-model enriching centrifuges.

It now has about 20,000 centrifuges, with half of them operating. Iranian officials recently signaled they are ready to freeze that number for now. But U.S. Secretary of State John Kerry said last week it was "crystal clear" that even 10,000 are too many. Diplomats say Washington wants no more than 2,000 of the machines.

Iran and the six powers on Friday agreed to a four-month extension of negotiations on a long-term nuclear deal that would gradually end sanctions on Tehran in exchange for curbs on its nuclear program, diplomats close to the talks said.

Iran will be allowed to access $2.8 billion of its frozen assets during the four-month extension, but most sanctions against Tehran will remain in place, U.S. officials said.

Iran, the United States, Britain, France, Germany, Russia and China had set a July 20 deadline to complete a long-term agreement that would resolve the decade-old dispute over Tehran's nuclear ambitions. But diplomats said they were unable to overcome significant differences on major sticking points.

The talks are taking place because of a preliminary agreement reached in Geneva in November 2013 that gave Iran limited sanctions relief in exchange for halting some nuclear activities and created time and space for the negotiation of a comprehensive deal to end the decadelong dispute.

Al Jazeera and the Associated Press