World powers continue to disagree over how to tackle the nuclear crisis with Iran after failing to reach consensus at a meeting in London.While Britain, France, Germany and the US want the UN Security Council to consider punishing Tehran, Russia and China remain opposed to sanctions. Iran has offered to return to talks with the EU3, drawing a chilly response from Britain which dismissed the offer as “vacuous”. But Russian Foreign Minister Sergei Lavrov said talk of sanctions was premature and that it was not the best way of solving the problem. China too favours diplomacy but has not said it would block any move to report Tehran to the Council. London, Paris and Berlin called off talks last week after Tehran removed UN seals on uranium enrichment equipment, fuelling Western suspicions it is seeking nuclear arms. They are calling for an emergency meeting of the UN nuclear watchdog, the International Atomic Energy Agency, next month. Iran denies it is seeking to develop atomic weapons and says it needs the technology to produce more electricity.