VIENNA - The European Union accused Iran on Thursday of having documents that show how to make nuclear warheads and joined the United States in warning Tehran it faced referral to the U.N. Security Council for possible sanctions.
Iran, meanwhile, suggested it was considering a compromise to reduce tensions.
Britain, in a statement on behalf of the 25-nation bloc, offered new negotiations meant to lessen concerns over Iran's insistence it be in full control of uranium enrichment - a possible pathway to nuclear arms.
"But Iran should not conclude that this window of opportunity will remain open in all circumstances," said a statement read by Peter Jenkins, the chief British delegate to the International Atomic Energy Agency, outside a closed meeting of the 35-nation board.
Diplomats described the statement as a veiled threat of Security Council referral. "It won't be open for a great deal longer," Jenkins said later when asked how much time Iran had to influence the language of a report to the Security Council.
The United States said separately that Iran cannot avoid referral to the Security Council for violating the Nuclear Nonproliferation Treaty but added that Washington and its European allies were delaying such a move to give Tehran a chance to defuse fears it wants to make nuclear arms.
"Iran must understand that the report to the council is required and will be made at a time of this board's choosing," said Gregory L. Schulte, the chief U.S. representative to the Vienna-based IAEA.
