Iran and world powers fail to resolve differences over Tehran's nuclear program.<br/> <br />European Union foreign policy chief Catherine Ashton<br/> <br />(SOUNDBITE) (English) EUROPEAN UNION FOREIGN POLICY CHIEF CATHERINE ASHTON, SAYING:<br/> <br />"It remains clear that there are significant gaps between the substance of the two positions. We've therefore agreed as follows: an early follow-on technical level meeting in Istanbul on July 3rd."<br/> <br />She said there was some progress.<br/> <br />(SOUNDBITE) (English) EUROPEAN UNION FOREIGN POLICY CHIEF CATHERINE ASHTON, SAYING:<br/> <br />"The fact is that they did begin to address the substance for the first time. But there is a very very long way to go."<br/> <br />The six powers representing the United States, China, Russia, France, Britain and Germany want Tehran to stop enriching uranium to levels that bring it closer to acquiring weapons-grade material.<br/> <br />If talks fail, financial markets could be hit by fears of conflict in the Middle East, and of higher oil prices, because Israel has threatened to attack Iranian nuclear sites if diplomacy fails to stop Iran developing a bomb.<br/> <br />Tehran denies any such aim, and says its nuclear program is purely for non-military purposes.<br/> <br />Deborah Lutterbeck, Reuters