Iran is currently reviewing a formal U.S. nuclear deal proposal as both sides remain deeply divided over uranium enrichment limits and sanctions relief.

The preliminary U.S. proposal came as a confidential U.N. report described an Iranian initiative that had multiplied Tehran’s stockpile of near-bomb-grade uranium.

Iran has further stepped up its production of highly enriched uranium, according to the UN nuclear watchdog. In a confidential report seen by the BBC, the International Atomic Energy Agency (IAEA) said Iran now possesses over 400kg of uranium enriched to 60% purity - well above the level used for civilian purposes and close to weapons grade,