Iran’s top nuclear official on Sunday warned Tehran would resume efforts to enrich uranium on an industrial scale if its case was reported to the UN Security Council, further raising the stakes in the crisis over its nuclear programme.

Tehran earlier this month moved to resume nuclear research, including some small-scale enrichment. But Ali Larijani, secretary of the Supreme National Security Council, which handles the nuclear issue, said in an interview with the Financial Times that a referral to the United Nations would force Tehran to broaden significantly the scale of such work.