U.S. Secretary of State Hillary Clinton says Washington expecting Iran to make “concrete commitments” in talks later this month to come clean on its nuclear program and live up to its international obligations.

Clinton said Tuesday that the talks between Iran and the so-called “P5+1” group — the United States, France, Britain, China and Russia, plus Germany — will not be an “open-ended session for both parties to talk around each other without ever coming to an agreement.”

She said President Barack Obama has made clear that Washington and its international partners are determined to prevent Iran from acquiring nuclear weapons, but that there is still time for sanctions and diplomacy to work.

The talks are set to take place in Istanbul April 13-14.

Iran's apparent willingness to return to the negotiating table follows moves by the United States and the European Union to tighten sanctions on Iran's banking sector and reduce purchases of Iranian oil.

Iran denies Western claims it is trying to develop atomic weapons and says its nuclear activities are purely for power generation and medical research.