Iran has ageed a deal to send uranium abroad following talks with the leaders of Turkey and Brazil.
Tehran says it will send 1,200 kilograms of low-enriched uranium to Turkey in return for highly enriched nuclear fuel for a research reactor.
Brazil, which enjoys warm diplomatic and commercial ties with Iran and helped mediate the talks, has opened a one-billion-dollar (780-million-euro) credit line for the Islamic Republic.
The move aims to dispel western concerns that Iran has nuclear military ambitions and to avoid being hit by UN sanctions.
Iran agreed in principle to a similar US-backed proposal in October that would have seen uranium processed in France and Russia, only for Tehran to make further demands that led the deal to break down.