The pressure is on at talks in Switzerland to find a preliminary deal on the Iranian nuclear issue.<br /><br /> Tehran is in negotiations with senior officials from the US, Britain, France, Germany, Russia and China.<br /><br /> The countries have a self-imposed deadline of midnight on Tuesday for an agreement.<br /><br /> Diplomats are worried that if there is no progress in overcoming differences this week the opportunity for a deal may be lost. <br /><br /> The talks are aimed at limiting Iran’s nuclear capacity so it cannot build an atomic bomb, in exchange for the easing of international sanctions.<br /><br /> But there are different views on what nuclear enrichment should be allowed and how fast sanctions can be eased. <br /><br /> Reihaneh Mazaheri, euronews’ correspondent in Lausanne, reported: “Iran and the delegates from the six world powers began their meetings this morning, the last day of the talks, at 7 o’clock. <br /><br /> “It is now a matter of waiting to see whether the fundamental disagreements can be resolved and whether this will b
