Iran appeared to side-step responding to proposals by world powers to defuse tensions over its nuclear program at talks in Kazakhstan on Friday, diplomats said, and instead came up with its own plan — a measure of the gulf between the two sides.
The six powers — the United States, Russia, China, France, Britain and Germany - had sought a concrete response from Iran to their February offer of modest sanctions relief if Tehran stops its most contentious nuclear work.
But instead Iranian negotiators outlined their own "specific" plan to resolve the dispute, which has been plagued by mutual mistrust and on-off negotiations for a decade.
"We are somewhat puzzled by the Iranians' characterization of what they presented," a Western diplomat said before talks finished for the day. "There has not yet been a clear and concrete response to the ... (six powers') proposal."
Iran's deputy negotiator Ali Bagheri did not say whether the offer of the six states was acceptable, but said the Iranian side had given a "detailed response to all the questions".
The dispute centers on Iranian efforts to enrich uranium, which world powers suspect are part of a covert drive to achieve a nuclear weapons capability.
The U.N. Security Council has demanded that Iran stop the process, in several resolutions since 2006.
But Iran argues it has the right to enrich uranium for peaceful purposes under international law and denies its nuclear work has military aims. It has refused to change course unless the big powers first recognize its right to enrichment and lift sanctions.
Stakes are high because Israel, widely assumed to be the Middle East's only nuclear-armed power, has threatened to bomb the Islamic Republic's nuclear sites if diplomacy fails to rein in a foe which it sees as bent on its destruction.
Chances for a quick deal are seen as distant, Western diplomats say, with Iran not expected to make any major decisions on nuclear policy until after its presidential election in June.
For years Iran has resisted ever-harsher sanctions and pressure to retreat from a nuclear program that enjoys broad support amongst its fractious political leadership.
Iran's chief negotiator, Saeed Jalili, said in a speech at a university in Almaty on the eve of the latest talks that their success hinged on "acceptance of the rights of Iran, particularly the right to enrichment".
The six nations, however, say this right only applies when nuclear work is carried out under sufficient oversight by U.N. inspectors, something Iran has refused to grant.
In Almaty, the second meeting in Kazakhstan's commercial hub in five weeks, Iranian negotiators appeared to oppose the six nations' strategy that the dispute could be solved by a series of steps starting with confidence-building measures.
The powers said in February that they wanted Iran to convince them it was serious about a final deal by stopping enrichment of uranium to 20 percent, an important technological advance en route to producing weapons-grade material, ship out some stockpiles and shutter a facility where such work is done.
In return they offered relief on sanctions on Iranian petrochemicals and trade in gold and other precious metals.
But Bagheri said no decisions should be made without a broader plan in sight, suggesting Iran wanted to know when and how sanctions would be lifted, particularly crippling measures against its oil industry.
"Actions which are referred to as confidence-building measures must be considered as part of a more comprehensive plan," he told reporters after Friday's talks wrapped up. "They are not separate."
But finding consensus on the end goal of negotiations will be difficult, with some members of the six-state group such as Russia more willing to lift sanctions than others, for example.
"Determining the broad principles governing the endgame is important but the entire diplomatic process should not become hostage to it," said Ali Vaez of the International Crisis Group.
Russia's negotiator, Deputy Foreign Minister Sergei Ryabkov, expressed some optimism, saying that while Iran needed to work harder in the negotiations, it had shown some seriousness in engaging the six nations' proposals.
"Iran has given an answer to the proposals of the six powers. It is the kind of answer that creates more questions," he was quoted saying by the Russian Interfax news agency. "But this shows that the negotiations are serious."
A Western diplomat said, however, there was "still a wide gulf between the parties".
"We are considering how we move on from here," the diplomat said.
For now, Iran may play for time, trying to keep diplomacy on track to avert new sanctions before the June election.
The six nations are wary of holding talks for their own sake, but Iran may have bought time for diplomatic efforts to resolve the dispute peacefully by converting some of its higher-grade uranium stockpile to nuclear reactor fuel.
If talks fail to produce sufficient progress, Western governments are likely to impose yet more economic penalties, with the double aim of pressuring Tehran while seeking to persuade Israel to hold back from any military action.
Israeli Prime Minister Benjamin Netanyahu told visiting U.S. senators on Thursday that Tehran's nuclear work must be stopped.
"We cannot allow a situation in which a regime that calls for our annihilation has the weapons of annihilation," he said.
U.S. President Barack Obama sought to cool tempers during a trip to Israel in March, saying diplomacy was the best option, but he hinted at possible military action as a last resort.
Additional reporting by Fredrik Dahl in Vienna, Zahra Hosseinian in Zurich and Steve Gutterman in Moscow; Editing by Alistair Lyon