The International Atomic Energy Agency (IAEA) has expressed “growing concern” about the Iranian nuclear programme due to an ongoing increase in highly enriched uranium. The stockpile of near weapons-grade material increased by around 23 kilograms to just under 165 kilograms between May and August, IAEA chief Rafael Grossi said in a report released on Thursday. According to experts, around 50 kilograms of uranium enriched up to 60% purity would be needed for a nuclear warhead. For use in nuclear weapons, it would have to be enriched to a level of 90%. Iran officially insists that it is not aimi…