ALMATY - Iran's chief nuclear negotiator said on Saturday there was some distance between the positions of Tehran and world powers but its disputed uranium enrichment could be a subject for confidence-building cooperation.Saeed Jalili spoke after two days of talks in the Kazakh city of Almaty failed to achieve substantive progress in the decade-old dispute over Iran's nuclear program."We proposed our plan of action and the other party was not ready and they asked for some time to study the idea," Jalili told a news conference. He said was now up to the powers to demonstrate willingness to take confidence-building steps.