Talks between Iran and a group of six nations over fears that Tehran's nuclear programme might be used to make weapons appeared to run into trouble shortly after they began.
A Western diplomat said Iran's response to the offer from the group fell short of what the six wanted and instead amounted to a "reworking" of proposals it made last year at negotiations that broke up in disagreement. The two sides remained a "long way apart on substance" as the talks adjourned in the Kazakh commercial capital, Almaty.
Iran is demanding international recognition of its right to advanced nuclear technology, but other countries are concerned that the Islamic Republic wants to use that expertise to make atomic arms.
Russia's Interfax news agency cited Deputy Foreign Minister Sergey Ryabkov, the head of his country's Almaty delegation, as saying the six won't be able to determine whether they can bridge differences with Iran until they meet again on Saturday. Comments by representatives of the sides laid out starkly different visions of what each sought from the other.
The six insist Iran cut back on its highest grade uranium enrichment production and stockpile, fearing Tehran will divert it from making nuclear fuel to form the material used in the core of nuclear warhead. They say Iran must make that move - and make it first - to build confidence that its nuclear programme is peaceful.
Iranian negotiator Ali Bagheri challenged the six countries on that point, telling reporters "what is being referred to as confidence-building measures are actions that both sides ... need to take" simultaneously.
He gave no specifics, but the comment could be an allusion to Iranian demands of sweeping sanctions relief instead of the offer from the six offering only a limited lifting of sanctions.
Iran also wants any nuclear concessions it makes to have specific limits instead of leading to others. Alluding to that demand, Mr Bagheri said his country wanted to nail down "the start of the process, the dimensions of the process and the final outcome of the process."
The six - the United States, Russia, China, Britain, France and Germany., are asking Tehran only to greatly limit its production and stockpiling of uranium enriched to 20%, which is just a technical step away from weapons-grade uranium. That would keep Iran's supply below the amount needed for further processing into a weapon.
Israel says Iran is only a few months away from the threshold of having material to turn into a bomb and has vowed to use all means to prevent it from reaching that point. The United States has not said what its "red line" is, but has said it will not tolerate an Iran armed with nuclear weapons.