Russian and Iranian officials have met in Moscow for talks on a compromise deal allowing Iran to conduct uranium enrichment on Russian soil.
A Russian official was quoted by the Itar-Tass news agency as saying no breakthrough was made in the talks, which were aimed at resolving a dispute with the West over Iran's nuclear activities.
In a joint statement, officials said discussions would continue at a future date.
Iran has said it agrees to the Russian deal in principle. But Iran's top negotiator, Ali Larijani, told reporters in Moscow Wednesday that his country has a sovereign right to enrich uranium for its nuclear reactors.
In Washington, a State Department spokesman Adam Ereli criticized the comments, saying it signaled a move in the wrong direction.
The United States and the European Union say Iran is pursuing nuclear weapons - a charge Tehran denies.Some information for this report was provided by AFP and AP.