WASHINGTON: The United States, Britain, France and Germany on Saturday expressed “serious concern” over Iran’s plans to launch a series of new centrifuges for its nuclear programme, urging Tehran to reengage with the UN nuclear watchdog. Iran’s announcement came after the four Western powers brought a censure motion targeting the Islamic republic at the 35-nation board of the International Atomic Energy Agency (IAEA). The resolution was adopted on Thursday. Iran has said it will activate “new and advanced” centrifuges in response to a resolution adopted by the International Atomic Energy Agency (IAEA) board censuring it for lack of cooperation. The motion was put forward by France, Germany, the United Kingdom and the United States at the 35-nation board of the United Nations nuclear watchdog and follows a similar one in June, criticised then by Iran as “hasty and unwise”.