London: British Foreign Secretary William Hague today said that Iran's "refusal to engage" world powers over its nuclear programme during talks in Istanbul was "extremely disappointing".
Two days of meetings ended today without progress and EU foreign policy chief Catherine Ashton - leading negotiations for Britain, China, France, Russia, the United States and Germany - said no more are planned.
"Iran's refusal to engage, including its insistence on pre-conditions that were clearly unrealistic, is extremely disappointing," Hague said.
"This is the clear and unified conclusion of the E3+3 (as the grouping of world powers is known). Until Iran recognises the need to engage meaningfully, the pressure on it will only increase.
"The choice is now Iran's. We have made every effort to make progress.
"We are committed to ensure a diplomatic resolution to our concerns and the door to future talks remains open.
"But Iran must demonstrate that it is serious about addressing international concerns about the nature of its nuclear programme or face increasing international isolation. It should not doubt our resolve."