Iran's nuclear chief says Tehran has enriched uranium almost up to the quality needed to fuel reactors.
The announcement of four-point-eight-percent enrichment, tops Iran's declaration of last month, when it said it had surpassed the three-point-six percent level.
To produce electricity, nuclear reactors require uranium enriched to five percent.
Uranium enriched to a low level can be used as fuel in reactors to generate electricity.
Further enrichment makes it suitable for use in nuclear weapons.
Yesterday, European nations backed by the United States outlined a planned UN Security Council resolution to give "mandatory force" to demands that Iran halt uranium enrichment.
U.S. Undersecretary of State Nicholas Burns says he hasn't "given up hope on diplomacy" though it sometimes must be "hard edged."
He predicts international support for sanctions within one to three months.