Six major powers gave Iran more details of their proposals to end a standoff over Tehran's nuclear program in talks in Istanbul on Monday, the European Union (EU) said, Reuters reported.
The EU's short statement on the expert-level talks between the six powers and Iran offered no clue how the proposals were received by the Iranian experts or whether any progress had been made.
The two sides agreed to hold the technical discussions at a February 26-27 meeting between officials in the Kazakh city of Almaty, when the United States, China, Russia, Britain, France and Germany offered modest sanctions relief in return for Tehran curbing its most sensitive nuclear work.
Iran says its nuclear program is peaceful but Western powers suspect Tehran of seeking nuclear weapons capability.
The statement by Michael Mann, a spokesman for EU foreign policy chief Catherine Ashton, reaffirmed that Monday's technical talks would be followed by another meeting at the political level in Almaty on April 5-6.
Western diplomats have made clear they want to see a substantive response from Iran to the six powers' proposals at the next meeting in Almaty.
"In Istanbul, experts from the six powers, led by nuclear expert Stephan Klement, gave Iran further details of the "revised confidence-building proposal" they put forward in Almaty," Mann said.
"The meeting also provided an opportunity for both (six-power) and Iranian experts to explore each other's positions on a number of technical subjects," he said, declining to go beyond the statement.
U.S. President Barack Obama insisted on Monday that "now is the time" for Iran to take meaningful steps to resolve its nuclear standoff with the West as he issued a direct appeal to the Iranian people before his first official trip to Israel.
Obama will hold talks in Israel on Wednesday with Prime Minister Benjamin Netanyahu, who repeatedly has called for a "credible" military threat against Iran and hinted at the prospect of a unilateral Israeli attack.
Western officials said the offer presented by the six powers in Kazakhstan included an easing of a ban on trade in gold and other precious metals, and a relaxation of an import embargo on Iranian petrochemical products.
In exchange, a senior U.S. official said, Iran would among other things have to suspend uranium enrichment to a fissile concentration of 20 percent at its Fordo underground facility and "constrain the ability to quickly resume operations there".
The proposals appeared to soften the six powers' previous demands.
Iran says it has a sovereign right to enrich uranium for peaceful purposes, and wants to fuel nuclear power plants so it can export more oil.