Europe is poised to compromise on Iran’s nuclear programme, in a step that could break the year-long stand-off over Tehran’s atomic ambitions.

A deal, floated by Tehran at a weekend meeting in Vienna, would rein in the most sensitive part of the programme as soon as formal negotiations began with the west. In response, the European Union is watering down its insistence that a suspension of enrichment activities must come before talks. But European diplomats stress that they will require Iran to allow United Nations inspectors to carry out spot-checks on its nuclear facilities to ensure that the Islamic republic has kept its side of the bargain.