Iran has rejected a demand by Western countries to ship out uranium stockpiles ahead of a fresh round of talks on its contested nuclear programme in Geneva.
Abbas Araghchi, the deputy foreign minister, said on state television on Sunday "shipping the material abroad is our red line. We do not allow shipment of even one gram of uranium from Iran". He, however, signalled flexibility on other aspects of its atomic activities.
"We will negotiate regarding the form, amount, and various levels of [uranium] enrichment," he said.
Araghchi's comments came ahead of new negotiations between Iran and the five permanent United Nations Security Council members and Germany, to be held in Geneva on October 15 and 16.
The talks will be the first since the election of Iranian President Hassan Rouhani, who has tried to improve relations with the West to pave the way for lifting economic sanctions.
Iran still insists its nuclear programme is peaceful and it only seeks reactors for energy and medical use, while the West suspects it of seeking to make a nuclear weapon.
Rouhani's election in June to succeed Mahmoud Ahmadinejad has raised hopes of a negotiated solution to a decade-old dispute over Iran's nuclear programme that could otherwise trigger a new war in the Middle East.
In negotiations since early 2012, world powers have demanded that Iran suspend 20-percent enrichment, send some of its existing uranium stockpiles abroad and close the Fordow underground site, where most higher-grade enrichment is done.
In return, they offered to lift sanctions on trade in gold and petrochemicals but Iran, which wants oil and banking restrictions to be removed, has dismissed that offer.
Since the Islamic Republic started started making 20-percent uranium gas in 2010 it has produced more than the 240-250kg needed for one atomic bomb.
It has also amassed stocks of low-enriched uranium gas that experts say would be enough for several bombs if processed much further to weapons-grade material. It has also sharply expanded its enrichment capacity in recent years.
Israel, which has threatened preemptive military action if it deems diplomacy a dead end, demands the total removal of Tehran's enriched uranium stockpiles along with a dismantling of its enrichment facilities.