Iran has increased its capacity to enrich uranium to higher grades, despite orders from the United Nations Security Council to stop such work, the UN nuclear watchdog said in a report on Friday, dpa reported.
Iran has tripled its capacity to enrich uranium to levels of 20 per cent at its Fordo facility and boosted the number of centrifuges enriching to below 5 per cent at its Natanz plant by 2,600 to 8,808, the report by the International Atomic Energy Agency (IAEA) said.
"This is significant," a senior diplomat closely following the IAEA's work in Iran said.
Iran's enrichment of uranium up to 20 per cent has caused concern in the West because it is theoretically much easier to turn such material into bomb-grade material than uranium enriched at below 5 per cent.
Iran has doubled the number of centrifuges for enriching to 20 per cent at Fordo, a fortified underground site near the city of Qom, according to a copy of the report obtained by dpa.
Iran has now made more than 100 kilograms of higher-enriched material, the document states.
This is less than half the amount needed for a nuclear warhead, according to nuclear experts.
But Iran has also made enough low-enriched uranium for at least four warheads, according to the figures in the document, which were overall not significantly higher for such material than in a previous IAEA report released in November.
The latest report comes two days after senior IAEA officials returned from a second trip to Iran without a commitment from Tehran to start answering questions about alleged nuclear weapons projects, and without having been allowed to see the key facility of Parchin.
"They said it's a military site and it needed the highest approval before access could be granted," the senior diplomat said.
In the report, IAEA Director General Yukiya Amano urged Iran to grant access to Parchin, where simulated nuclear warheads were allegedly tested.
Officials in Teheran this week gave the IAEA a document that aimed to answer allegations about nuclear projects, but contained nothing but dismissals of the agency's concerns, "largely on the grounds that Iran considered them to be based on unfounded allegations," the IAEA said.
The IAEA received information from various intelligence agencies in addition to gathering its own.
"The information indicates that: prior to the end of 2003 the activities took place under a structured programme; that some continued after 2003; and that some may still be ongoing," Amano said in the report.
Senior diplomats said the IAEA had made progress with Iran on tackling the country's alleged nuclear weapons projects, but higher-level Iranian officials prevented a solution to the stand-off at the last minute.
Iran did not agree to a plan drafted in January, as it did not want to allow nuclear inspectors to ask follow-up questions and return to issues once they had been addressed, according to the diplomats.
Iran has also raised the issue of the four nuclear scientists who were assassinated in the past two years, in response to calls for IAEA access to such experts.
During their two missions since January, the IAEA team also unsuccessfully sought information about a Russian scientist who was allegedly involved in the tests at Parchin.