Secretary of State Hillary Clinton says the United States and other major world powers have agreed on a draft resolution that could impose a fourth round of United Nations sanctions on Iran.
Clinton made the announcement in testimony to a Senate committee Tuesday, a day after Iran announced a plan to send some of its enriched uranium to Turkey in exchange for nuclear fuel.
The Security Council is set to hold consultations on the sanctions draft Tuesday.
Clinton said the plan followed talks among the five permanent Security Council members - the United States, Britain, China, France and Russia, as well as Germany.
She noted the agreement had been reached in cooperation with China and Russia - two nations that have previously resisted imposing more sanctions on Tehran.
On Monday, Iran signed an agreement with Turkey and Brazil to send 1,200 kilograms of low-enriched uranium to Turkey in exchange for higher-enriched nuclear reactor fuel to be used in a medical research reactor in Tehran.
Both Turkey and Brazil are non-permanent members of the Security Council.
Iran's Foreign Ministry spokesman Ramin Mehmanparast accused Western nations Tuesday of "seeking excuses" to avoid resolving the nuclear dispute with his country.
Turkey's Foreign Minister Ahmet Davutoglu said talk of sanctions could "spoil the atmosphere" and lead to an "escalation" of statements that might "provoke" Iranian public opinion.
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.
Israeli Prime Minister Benjamin Netanyahu met with top Cabinet members Tuesday to consider a response to the Iranian plan.
Israel views a nuclear-armed Iran as a threat to its existence because of repeated calls by Iranian leaders for the demise of the Jewish state.