Rice told the UN General Assembly that the world body "must be able to deal with great challenges like terrorism and nuclear proliferation, especially when countries like Iran threaten the effectiveness of the global non-proliferation regime."

But after a round of US lobbying for world support to haul the Iranians before the Security Council for possible sanctions, Rice signaled a US openness to further negotiations between Tehran and Britain, France and Germany.

"When diplomacy has been exhausted, the Security Council must become involved," the chief US diplomat said.

"Iran should return to the negotiations with the EU-3 -- and abandon forever its plans for a nuclear weapons capability," she said.

All rights reserved. � 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.