Iranian officials ruled out any freeze in uranium enrichment on Saturday at the start of talks over Tehran's nuclear program attended for the first time by a senior US diplomat. “Any kind of suspension or freeze is out of the question,” an Iranian official told Reuters, rejecting the main condition set by the United States and other major powers for formal negotiations to end the long-running dispute. The high-level US participation in the one-day meeting in Geneva, together with Iranian comments playing down the likelihood of an attack by the United States and Israel, had raised hopes of progress and helped ease record oil prices. But the optimism was tempered by US insistence that despite the presence of its envoy William Burns, real negotiations cannot begin until Iran has frozen sensitive nuclear work, a step Tehran has repeatedly rejected. Iran's ambassador to Switzerland said Iran would not accept a freeze. “It is not in Iran's agenda to discuss this issue,” Keyvan Imani told reporters. “As our supreme leader (Ayatollah Ali Khamenei) clearly said, our path is very clear: We are not going to abandon our rights.” Khamenei said on Wednesday Iran was ready to negotiate, but showed no sign of backing down on the Islamic Republic's refusal to halt atomic activities.