BBC News reports Iran's supreme leader Ayatollah Ali Khamenei has backed talks with world powers but warned Tehran will never give up its nuclear program. He said Iran had agreed to the talks to "break the hostile atmosphere" with the international community. But he urged his negotiators in Vienna not to yield to "coercive words." Iran and the six world powers involved in the talks are working to secure a comprehensive deal to replace an interim agreement that expires in July. The U.S., Russia, China, Britain, France and Germany want to see Iran scale back its enrichment of uranium, which they fear could be used to make a nuclear bomb.Tehran says its nuclear work is purely peaceful and hopes to agree a deal in return for a permanent lifting of sanctions.