"We cannot give up enrichment because it is an achievement of our own scientists. And now, more than that, it is a question of national pride," Araghchi told Fox.

Iran is threatening to raise uranium enrichment to weapons-grade levels and exit the Nuclear Non-Proliferation Treaty (NPT) if Western powers move forward with reimposing United Nations sanctions, according to Iranian state media. The warning follows mounting pressure from the United States and its European allies.

CBS News has learned that a new assessment of the U.S. strikes on Iranian nuclear sites in June finds that only one of three facilities was possibly destroyed. CBS News senior national security correspondent Charlie D'Agata has the details.

Tehran says air defences are restored after Israeli and U.S. strikes, as nuclear talks with Europe may be the last chance to avoid wider conflict.

Iran has replaced air defences damaged during last month's conflict with Israel, Iran's Defah Press news agency reported on Sunday quoting Mahmoud Mousavi, the regular army's deputy for operations.

Iran has replaced parts of its air defence network damaged during last months conflict with Israel, according to Defah Press, quoting Mahmoud Mousavi, deputy chief of operations for Irans regular army.