Iran says it has found major new uranium deposits and is planning to expand its nuclear power programme.
It said 16 sites had been identified as suitable for the construction of new power plants over the next 15 years.
Iran said the find – which has not been independently confirmed – would treble the size of known uranium deposits.
Under UN sanctions, Iran is banned from importing nuclear material. It is due to hold talks with Western powers on Tuesday about its nuclear programme.
The US and its allies are widely believed to be planning to offer Iran some relief from sanctions at the talks in Almaty, Kazakhstan.
France confirmed a “substantial” new offer would be made, French news agency AFP quoted the foreign ministry as saying.
Three rounds of meetings in Moscow ended last June in stalemate.
Iran denies charges that it is secretly developing atomic weapons and insists that as a signatory of the Nuclear Non-Proliferation Treaty (NPT) it is entitled to develop a nuclear power programme.
But tightening sanctions have squeezed Iran’s economy, with oil revenue slashed, a currency that has nosedived in value, and growing unemployment.