Iran will not accept any "backward steps" on its nuclear programme, specifically on the enrichment of uranium, a top official said Saturday, dismissing US calls for more curbs.

Deputy Foreign Minister Abbas Araqchi, a member of Iran's nuclear talks team, was responding to comments by the lead US negotiator Wendy Sherman who called on Iran to "finish the job".

Sherman's remarks came in a speech given Thursday at a Washington think-tank where she cited the "size and scope" of Iran's enrichment as a barrier to a deal.

"Iran's leaders would very much hope that the world would conclude that the status quo -- at least on this pivotal subject -- should be acceptable, but obviously it is not," she said.

Araqchi rejected Sherman's suggestion.

"We will not back down on our nuclear rights but we are ready to take transparency and confidence-building measures," the official IRNA news agency quoted him as saying.

"There will be no backward steps" in the nuclear programme, he said.

The six powers leading the talks with Iran -- Britain, China, France, Russia, the United States plus Germany, known as the P5+1 -- have set November 24 as the deadline for a comprehensive deal.

The aim is to close Tehran's avenues towards developing an atomic bomb, by cutting back its enrichment program, shutting down suspect facilities and imposing tough international inspections.

In return, the global community would suspend and then gradually lift crippling economic sanctions imposed on the Islamic republic.

But the two sides, despite long-running talks, remain far apart on how to reconcile their objectives.