Iranian officials have insisted that enrichment is an inalienable right and that talks must be unconditional. The process can produce fuel for nuclear power plants or material for atomic bombs.

The country denies accusations by the US and others that it is seeking to develop nuclear weapons, saying its program would only generate energy.

Russian President Vladimir Putin said Thursday that Iran was prepared to negotiate on the basis of the incentives.

Speaking after talks with Ahmadinejad in Shanghai, Putin said: "The Iranian side responded positively to the six-nation proposal for a way out of the crisis."