A six-nation meeting has ended in New York without any agreement about Iran's continuing defiance of United Nations resolutions on its nuclear programme.
The United States, Russia, China, Britain, France and Germany are trying to persuade Iran to halt uranium enrichment, despite Iranian insistence that its nuclear programme is entirely peaceful.
The meeting focused on Iran's performance since the beginning of the engagement process four months ago.
During that period Iran rejected a compromise proposal to enrich its stock of uranium outside the country and was forced to acknowledge it was building a secret nuclear plant.
A senior European official said the six powers agreed that Iran's response had been inadequate and that further measures would now be considered.
However there was no agreement on whether these measures would include new sanctions.
President Barack Obama earlier set a deadline of 31 December, 2009, for Iran to respond to an offer of economic and political incentives in exchange for halting the programme.
Three rounds of sanctions have already been imposed on Iran.
