Iran signaled to the West on Monday that it will not allow its enriched uranium to be moved out of the country, in spite of international demands.
Iranian state-run Press TV cited unnamed officials in Tehran as saying the Islamic Republic was looking to hold on to its low-enriched uranium and buying what it needed for the Tehran reactor abroad.
The report indicated that Iran will not meet terms the West said it agreed to — including transferring most of its stock of enriched uranium, the potential base for fissile warhead material. Tehran says it needs enriched uranium for nuclear fuel.
"Buying nuclear fuel from abroad does not mean Iran will stop its uranium enrichment activities inside the country," Ali Shirzadian, spokesman for Iran's Atomic Energy Organization, told Iran's official IRNA news agency.
"If the talks do not bring about Iran's desired result ... we will start to make 19.7 percent enriched uranium ourselves," Shirzadian told Reuters a few hours before the talks were due to start.
The U.S. says Iran is now one to six years away from being able to make such arms, should it choose to.
Meanwhile, the head of the U.N. nuclear agency says talks with Iran's International Atomic Energy Agency delegation were off to a"good start" in Vienna.
Mohamed El Baradei, who heads the International Atomic Energy Agency, attended the first day of talks Monday. He spoke of "quite a constructive meeting."
"We are off to a good start," Baradei said.
Even if Tehran agrees, it could still try to resist pressure to hand over most of its stock in one batch, insisting instead on sending small amounts out of the country. Iran still has enough fuel for the Tehran reactor to last until mid-2011.
Monday's Vienna talks between Tehran and the U.S., Russia and France, focused on the technical issue with huge strategic ramifications.
Progress would strengthen confidence on the part of the U.S. and five other big powers trying to persuade Iran to dispel fears about its nuclear program that this time Tehran is serious about reducing tensions and ready to build on Oct. 1 Geneva talks with six world powers.
Beyond that, it could give the international community more negotiating space by delaying Tehran's ability to turn what is now a civilian uranium enrichment program into an assembly line producing fissile warhead material
The talks Monday will attempt to implement what Western officials say Iran agreed to during the Geneva talks; letting a foreign country — most likely Russia — turn most of its low-enriched uranium into higher grades to fuel its small research reactor in Tehran.
That would mean turning over more than 1,200 kilograms of low-enriched uranium — more than 2,600 pounds and as much as 75 percent of Iran's declared stockpile. Tentative plans are for further enrichment in Russia and then conversion in France into metal fuel rods for the Tehran reactor.
Iranian agreement to such terms would be significant because 1,000 kilograms is the commonly accepted threshold of the amount of low-enriched uranium needed for production of weapons-grade uranium enriched to levels above 90 percent.
Based on the present Iranian stockpile, the U.S. has estimated that Tehran could produce a nuclear weapon between 2010 and 2015, an assessment that broadly jibes with those from Israel and other nations tracking Tehran's nuclear program.
If most of Iran's declared stock is taken out of the country, further enriched abroad and then turned into fuel for the Tehran reactor, any effort to make nuclear weapons would be delayed until Iran again has enriched enough material to turn into weapons-grade uranium.
"It buys some time," said David Albright of the Washington-based IISS, which has closely tracked Iran for signs of any covert proliferation. But Albright added that Iran could replace even 1,200 kilograms of low-enriched uranium "in little over a year" at its present rate of enrichment.
The Associated Press contributed to this report.