ALMATY, Kazakhstan: Negotiations with world powers over how to curb Iran's nuclear program have reached a "turning point" for the better after nearly breaking down last year, the Islamic republic's top official at diplomatic talks said Wednesday at the close of two days of delicate discussions aimed at preventing Tehran from building an atomic arsenal.

While still guardedly optimistic, the comments by Saeed Jalili, the secretary for Iran's Supreme National Security Council, marked a significant step forward in a years-long process that has been rife with suspicions and, if it fails, could lead to a new Mideast war. The Obama administration is pushing for diplomacy to solve the impasse but has not ruled out the possibility of military intervention in Iran to prevent it from acquiring a nuclear weapon.

Jalili said a new offer this week by the world powers to compromise is more realistic than what has been offered in the past. He described the new offer - including some relief from international sanctions - as a step to build confidence between the two sides after similar negotiations in Moscow were nearly derailed last June.

"In this round of talks we have witnessed that despite all the attitudes during the last eight months, they tried to get closer to our viewpoints," Jalili told reporters at the close of two days of talks in Kazakhstan's largest city. "We believe this is a turning point."

Jalili did not detail what the sanctions relief might include, or what Iran was willing to do to in exchange.

But he would not budge on Iran's longtime instance, and a main sticking point in the talks, that it has the right to enrich uranium to 20 percent - a point that is just steps away from being able to be converted into nuclear warheads.

"Whatever we need, we will of course pursue that - whether it is 5 percent or 20 percent," Jalili said. "It is important to us to have the 20 percent."

EU foreign policy chief Catherine Ashton, who is leading the negotiations, refused to discuss what the potential deal included.

"I hope the Iranians are looking positively on the proposals we put forward," Ashton said. "I believe in looking at what the results are."

"We'll have to see what happens next," Ashton said. "But we approach this with the absolutely united view that we need to see the progress necessary for the confidence the international community needs."

Technical experts for each side will meet in Istanbul in mid-March to discuss the world powers' offer and the high-level diplomats will re-convene again April 5 in Almaty.

Off-and-on talks between Iran and the world powers - the United States, China, Russia, Britain, France and Germany - began after the six offered Tehran a series of incentives in 2006 exchange for a commitment from Tehran to stop enrichment and other activities that could be used to develop weapons.

Tehran maintains it is enriching uranium only to make reactor fuel and medical isotopes, and insists it has a right to do so under international law. It has signaled it does not intend to stop, and U.N. nuclear inspectors last week confirmed Iran has begun a major upgrade of its program at the country's main uranium enrichment site.

Western negotiators are banking on hopes that easing some sanctions will make Tehran more agreeable to halting production of 20 percent enriched uranium. They also want Iran to suspend enrichment in its underground Fordo nuclear facility, and to ship its stockpile of high-grade uranium out of the country.

But Tehran has said shuttering Fordo is out of the question and that Iran first wants the U.N. Security Council to withdraw all of the sanctions it has heaped on the nation.

Iran has been unimpressed with earlier offers by the powers to provide it with medical isotopes and lift sanctions on spare parts for civilian airliners, and new bargaining chips that Tehran sees as minor are likely to be snubbed as well.

Iran insists, as a starting point, that world powers must recognize the republic's right to enrich uranium.