AFP quotes a European diplomat as saying the letter proposes a meeting with negotiator Ali Larijani to examine the possibility of resuming talks.
The UN's nuclear watchdog, the International Atomic Energy Agency (IAEA), on 24 November put off a decision
on whether to refer Iran to the UN Security Council in order to give time for Russian diplomacy to resolve the nuclear crisis.
Under the Russian plan, Iran would enrich uranium on Iran's behalf. But Iranian Foreign Ministry spokesman Hamid Reza Asefi said today that the coming talks would have to provide "concrete guarantees" that Iran can conduct fuel-cycle work on its own soil.
"We believe that the negotiation issue is clear," Asefi said, according to Reuters. "The issue is firm guarantee to produce nuclear fuel cycle in Iran. This should be the subject of the negotiations."
The United States and other governments have accused Tehran of secretly trying to develop nuclear weapons, a charge that Iranian officials have consistently denied.
International fears grew after the IAEA accused Iran in June 2003
of having "failed to report certain nuclear materials and activities." The IAEA at the time encouraged Iran to sign the so-called Additional Protocols of the Nuclear Nonproliferation Treaty (NPT) and urged it to allow unannounced inspections of its nuclear sites.
THE COMPLETE PICTURE: RFE/RL's complete coverage of controversy surrounding Iran's nuclear program.
An annotated timeline
of Iran's nuclear program.