By Steve Gutterman
MOSCOW (Reuters) - Russian President Vladimir Putin told Iran's Hassan Rouhani on Monday there was a "real chance" for a nuclear deal, two days before Tehran resumes talks with world powers, hoping to end a decade-long standoff over its atomic program.
Russia is one of six world powers negotiating a proposal that would ease sanctions on Tehran if it suspends some parts of a program that many countries, particularly in the West, fear is aimed at developing nuclear weapons capability.
"Vladimir Putin underlined that at the moment a real chance has appeared to find a solution to this long-running problem," the Kremlin said after Putin telephoned Rouhani, elected president in June vowing to mend Iran's international relations.
Israel opposes any deal to lift sanctions and France, one of the world powers at the talks, has said it would not back any such deal unless it were certain Iran has renounced any nuclear weapons program.
Iran denies it is seeking weapons. But its refusal so far to curb its program and lack of full openness with U.N. inspectors have drawn several rounds of U.N. sanctions and much harsher measures from the United States and Europe.
Two of the steps Western powers want Iran to take in the initial phase of any deal are to stop producing uranium enriched to a fissile concentration of 20 percent - a relatively short step from weapons-grade material - and to produce less 3.5 percent enriched uranium.
Russian Foreign Minister Sergei Lavrov suggested Iran was prepared to do both.
"The steps that Iran is prepared to set out as its commitments are quite, quite substantial and go in the direction of the demands of the international community at a much faster pace, in fact, than had been expected," Lavrov said, according to Russia's official gazette, Rossiiskaya Gazeta.
"This applies primarily to suspending enrichment above 5 percent and restricting capacity for 5 percent enrichment within certain parameters," he said.
Russia, which built Iran's first nuclear power plant, backs Iran's desire for recognition of its right to enrich uranium and opposes any additional sanctions.
Rouhani, in a likely reference to French and Israeli demands for more concessions, struck a cautious tone.
"Good progress has been made in the Geneva nuclear talks, but excessive demands could put a win-win agreement in jeopardy," he told Putin, according to Rouhani's website.
"In our view, conditions must not be created that give rise to damaging the will to achieve an agreement and reach a satisfactory conclusion."
EU foreign policy chief Catherine Ashton, who represents the nations talking to Tehran - Russia, China, the United States, Britain, France and Germany - said her aim for the talks was: "to see whether we can find a way to build confidence in the exclusively peaceful nature of Iran's nuclear program."
She said the group of six was "united in our determination to see if it can be done and united in our determination that if we do any kind of agreement it must be a good agreement."
(Additional reporting by Isabel Coles and Adrian Croft; Editing by Timothy Heritage and Robin Pomeroy)