The head of the United Nations says Iran must do more to show its nuclear program is not a threat.
U.N. Secretary-General Ban Ki-moon Thursday urged Iran to clarify its nuclear intentions, saying Tehran's handling of the dispute has led to "a serious lack of trust."
The U.N. chief, speaking in Brazil, also welcomed the efforts of Brazil and Turkey to broker a possible deal with Iran.
German Chancellor Angela Merkel also criticized Iran Thursday, saying her country would continue to back new sanctions because Iran continually fails to show transparency.
Earlier, Russia's foreign minister rejected Iran's criticism of the Kremlin's support for new sanctions against Tehran.
Foreign Minister Sergei Lavrov dismissed statements by Iranian President Mahmoud Ahmadinejad as "emotional," telling reporters in Moscow that Iran's response to Russia's efforts has been unsatisfactory.
Later Thursday, Russia's foreign ministry said Lavrov spoke by phone with Iranian Foreign Minister Manouchehr Mottaki, telling him that Russia would still work actively for a diplomatic settlement.
Iran's president on Wednesday condemned Russia's support for new sanctions, accusing Moscow of bowing to U.S. pressure.
Mr. Ahmadinejad also called on both the United States and Russia to accept a nuclear fuel swap deal brokered by Turkey and Brazil. He said it will be the last chance to resolve the nuclear stand-off.
The U.S. calls the proposed deal a "transparent ploy." But Lavrov said Russia would welcome the deal if Iran agrees to implement it fully.
The United States and other Western nations suspect Iran is enriching uranium to try to build nuclear weapons, but Iran insists its nuclear program is for peaceful purposes.
Earlier this week, Iran submitted a letter to the International Atomic Energy Agency outlining a plan in which Iran would send 1,200 kilograms of low-enriched uranium to Turkey in exchange for higher-grade fuel for a medical research reactor in Tehran.
The proposal resembles previous plans to provide Iran with nuclear fuel, while limiting its supply of uranium that could be used to produce an atomic weapon.
The five permanent members of the U.N. Security Council - the United States, France, Britain, China and Russia - have approved a draft resolution for a fourth round of sanctions on Iran for refusing to stop the suspect parts of its nuclear program.
Some information for this report was provided by AP, AFP and Reuters.