VIENNA (REUTERS) - Iran has begun enriching uranium at its underground Fordow site in the latest breach of its deal with major powers, the UN nuclear watchdog confirmed on Monday (Nov 11), adding that Teheran's enriched uranium stock has continued to grow.

Iran is breaching the deal's limits on its nuclear activities step by step in response to Washington's withdrawal from the accord last year and its renewed sanctions on Teheran.

Teheran says it can quickly undo those breaches if Washington lifts its sanctions.

In a quarterly report, the International Atomic Energy Agency policing the deal said Iran's reserve of enriched uranium and the purity to which it refines uranium remain above the deal's limits.

Teheran is also enriching with more advanced centrifuges and enriching at Fordow, which the deal forbids.