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.

The U.N. atomic agency reports that Iran hasn’t cooperated with a nuclear probe, raising the prospect of a snapback of sanctions on Tehran.