The U.N. nuclear watchdog says Iran has further increased its stockpile of uranium enriched to near weapons-grade levels.

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, and a near 50% increase in three months.

Iran has continued to produce highly enriched uranium at a pace of roughly one nuclear weapon’s worth a month over the past three months despite talks between Washington and Tehran on a new nuclear deal,