Iran said on Friday it had started activating “new advanced centrifuges”, expanding its nuclear activity in a move that risks escalating tensions with the west, weeks before US president-elect Donald Trump takes office.

Iran’s foreign ministry said the activation of the centrifuges, used to enrich uranium, was in response to a US and European-backed resolution by the board of the International Atomic Energy Agency that rebuked Tehran for its lack of co-operation with the UN nuclear watchdog.