With a looming deadline on a nuclear agreement, western leaders are trying to pursuade Iranian negotiators that a deal is in Tehran's best interests.<br /> <br />Representatives from the United States, Britain, France, Germany, Russia and China are in Vienna for a final round of talks with Iran aimed at curbing its nuclear program in exchange for the removal on economic sanctions.<br /> <br />British Foreign Secretary Philip Hammond.<br /> <br />(SOUNDBITE) (English) BRITISH FOREIGN SECRETARY, PHILIP HAMMOND, SAYING:<br /> <br />"There is clearly an interest on the Iranian side to get a deal done, the prize for Iran is huge - access to very large amounts of frozen assets, the ability to trade freely with the world again and the ability to reset relationships with the international community, so there is a huge prize on the table for Iran. I think we all want to get the deal done but are also all aware of the very complex issue that are at stake here."<br /> <br />Chief among those issues, is trust.<br /> <br />Western
