World powers and Iran have begun two days of talks on Tehran's nuclear program.
The discussions opened Friday in Almaty, Kazakhstan among the five permanent members of the U.N. Security Council, plus Germany and Iran.
A spokesman for European Union foreign policy chief Catherine Ashton told reporters Friday that the group hopes Iran will present a response to proposals made to Iran in February. Those proposals include Iran closing a nuclear facility and getting rid of its stockpile of enriched uranium in exchange for permission to trade some products now under international sanctions.
On Thursday, Iran's chief nuclear negotiator, Saeed Jalili, demanded that world powers recognize an Iranian right to enrich uranium.
The United States and its allies accuse Iran of amassing highly-enriched uranium as part of a covert drive to make nuclear bombs. Tehran insists its nuclear program is peaceful.
A senior U.S. official said Wednesday the world powers want Iran to give a "concrete and substantive" response to their proposal.
The U.S. official reiterated that President Barack Obama prefers diplomacy, but is leaving "all options" on the table to deal with the situation.