U.S. President Barack Obama warned Iran Friday it must "come clean" about its disputed nuclear program in international talks next week or else face possible sanctions from a united world community.
Mr. Obama, speaking at the end of the G20 summit in Pittsburgh, Pennsylvania, told Iran it would remain on a path to "confrontation" with global powers unless Tehran agreed to disclose all its nuclear activities.
He said the international community had displayed an "unprecedented show of unity" on Iran at the United Nations General Assembly and G20 summit this week.
The U.S. president stressed he preferred diplomacy in dealing with Iran over its nuclear program but would consider tough sanctions if dialogue did not work. He also did not rule out military action.
Mr. Obama, British Prime Minister Gordon Brown and French President Nicolas Sarkozy said earlier Friday that Iran has been building a covert, underground plant to produce nuclear fuel.