In return, the countries offered to supply Tehran with fuel for its medical research reactor, which requires 20% uranium, and to ease sanctions.

CNN: Little headway in Iranian nuclear talks

The Iranian government says it requires 20% enriched uranium for its medical research reactor in Tehran, but Western experts say it could be converted to weapons-grade material within six months.

BBC: EU imposes new sanctions on Iran

The United States and other leading nations have been negotiating with Iran to send low-enriched uranium abroad to be turned into material for use in medical research and treatment at a reactor in Tehran.

CNN: STORY HIGHLIGHTS

It could also be possible to provide similarly enriched fuel, perhaps from France, for the Tehran Research Reactor (TRR) and LEU targets for producing medical isotopes in the reactor.

ECONOMIST: Iran and nuclear weapons

Rather than sit down with the six, it may be hoping to revive talks about a separate proposal for Russia, France, America and the IAEA to help it find replacement 20%-enriched fuel for a research reactor in Tehran that supplies medical isotopes.

ECONOMIST: Iran pockets Bushehr and plays on

It was also now fuelling the Tehran Research Reactor used to make medical isotopes with its own domestically produced uranium enriched to 20%.

ECONOMIST: Nuclear diplomacy