Iran is producing highly-enriched uranium faster than called for by the law under which it started the process of enriching to 20% fissile purity last month, diplomats and a report by the UN nuclear watchdog said. As part of a recent acceleration of its breaches of its 2015 nuclear deal with major powers, Iran has begun refining uranium to 20% at Fordow, a site that was built in secret inside a mountain where the deal says Iran cannot enrich at all. Until last month Iran had not enriched beyond 4.5% purity - above the deal's limit of 3.67% but still far below the 20% it achieved before the deal, or the 90% that is weapons-grade. Uranium is considered highly enriched as of 20%. "They are producing 15 kg a month of uranium enriched to 20%. That is their production rate," a senior diplomat said.