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The United States and other Western powers still have serious concerns about Iran's nuclear program, despite Tehran's agreement to send some of its enriched uranium to Turkey.
Iran's Foreign Ministry spokesman (Ramin Mehmanparast) Monday said Tehran has agreed to swap 1,200 kilograms of low-enriched uranium - about half its reported stockpile - for higher-enriched nuclear reactor fuel.
A White House spokesman (Robert Gibbs) said the new proposal does not change the steps the U.S. is taking to hold Iran accountable, including possible sanctions. He issued a statement saying Iran's comments that it would continue its "20 percent enrichment" program are a direct violation of U.N. Security Council resolutions.
British junior foreign minister Alistair Burt said work on a possible fourth round of sanctions against Iran must continue until Tehran shows the international community that its nuclear intentions are peaceful.
French Foreign Ministry spokesman Bernard Valero said negotiators should not "deceive" themselves by believing the agreement would resolve problems with Iran's nuclear program.
Russian President Dmitri Medvedev cautiously welcomed Iran's agreement. However, he said more consultations with all of the powers involved are needed, partly to address concerns that Iran continues to enrich uranium.
Britain, France, Russia and the United States are permanent U.N. Security Council members.
Iran says it will officially notify the United Nations nuclear agency (IAEA) of the agreement within a week. The latest IAEA report suggests 1,200 kilograms of low-enriched uranium would amount to about half of Iran's stockpile.
In February, the nuclear watchdog agency calculated Iran had stockpiled 2,065 kilograms.
Turkish Foreign Minister Ahmet Davutoglu said the deal was reached by the foreign ministers of Brazil, Iran and Turkey after almost 18 hours of negotiations in Tehran. He said there is no longer any need for U.N. sanctions against Iran.
Previously, Iran was not receptive to a U.N.-backed deal that called for it to send low-grade uranium to Russia, where it would be processed into highly enriched uranium to power a medical research reactor in Tehran. Iran had insisted on a simultaneous exchange of nuclear material on its territory.
The United States and its Western allies accuse Iran of working to make a nuclear weapon. Iran says its atomic program is for peaceful purposes.