Talks between Iran and six major powers over Tehran's nuclear program on Thursday opened the door to improve relations as Iran agreed to allow U.N. inspectors into a newly disclosed uranium enrichment plant.<br/> <br/>Both the United States and Iran described the talks between Tehran and the six powers – Britain, France, Germany, Russia, China and United States – as productive and agreed the contacts would be resumed by the end of the month.<br/><br/>In Washington, President Barack Obama described the meeting in Geneva as a constructive beginning but insisted that Iran must demonstrate that it was not seeking nuclear weapons. Iran insists its nuclear program is designed only for electrical power generation.<br/> <br/>The conciliatory tone of the discussions, which included the highest-level direct talks in three decades between Iranian and U.S. officials, appeared to ease some of the tension between Tehran and the United States and its European allies, which have been threatening Iran with stringent new sanctions.<br/>