"The talks are not going easily, but we are counting on reaching a positive result," Putin sad on Wednesday during a visit to Azerbaijan.
The Russian leader said that the Kremlin's offer to enrich uranium for Tehran to avert suspicions that the Iranians could divert the nuclear fuel for atomic weapons should be "perfectly acceptable" to Iran and could be used as "a means to solve the problem".
"We are not losing optimism," said Putin. "We are waiting for a final response from the Iranian negotiators, and we hope for a positive result."
The two countries' negotiators ended two days of inconclusive talks in Moscow on Tuesday on the Russian initiative, which comes amid Western pressure to impose sanctions against Iran.
Russian newspapers on Wednesday cited Iranian officials as saying Iran was not ready to accept Russia's plan because Tehran insisted on the right to conduct its own enrichment activities.
"There are no reasons at this stage to resume dialogue," the Vedomosti daily quoted an unidentified official close to the Iranian delegation as saying.
The US and the EU-3 are counting
on Russia to prevent a showdown
The Iranian embassy in Moscow declined to comment on the
outcome of the talks.
Tehran's top negotiator, Ali Hosseinitash, labelled the Moscow meeting "positive and constructive", but some Russians voiced concern that Iran was using the proposed Kremlin compromise to stall and avert international sanctions.
An Iranian diplomat cited by the Vremya Novostei daily said Iran wanted Russia to produce large-scale enriched uranium for it but needed a domestic uranium enrichment programme to create "the basis for independence in the nuclear sphere".
The diplomat also was not identified.
The Iranian official cited by Vedomosti said that at the talks, Iran demanded that the Russian enrichment plan function for only three to five years and insisted on the Iranian right to conduct the initial stages of uranium enrichment on its own territory.
But the Russian side, the official said, was adamant that the Iranians restore the freeze on enrichment they broke last month when they resumed small-scale activities and that Iran content itself with paying Russia for supplies of enriched fuel for its atomic power facilities.
Iranian officials say they need a
domestic enrichment programme
The Interfax news agency on Wednesday cited an unidentified diplomat in Moscow close to the negotiations as saying that the two sides had reached a deadlock, describing the Russian demand for a freeze on enrichment as "unacceptable" for Iran.
The UN nuclear watchdog, the International Atomic Energy Agency, holds a 6 March meeting that could start a process leading to punishment by the Security Council, which has the authority to impose sanctions on Iran.
Enriched uranium can be used as fuel for a nuclear reactor or fissile material for a bomb. Iran says it is pursuing peaceful nuclear energy but Western nations fear it is seeking an atomic weapon.