Deputy Foreign Minister Sergei Ryabkov said the two sides had made no progress since the last round of top-level negotiations were held in Moscow at the end of June 2012.

But he stressed that pressure will be high on both Iran and the world powers to climb down from their respective positions and seek middle ground at the February 26 meeting in Almaty.

"Despite everything, I would very much hope to see the upcoming round result in -- if not an outright breakthrough -- then serious progress," Ryabkov said in a wide-ranging interview with the state-run RIA Novosti news agency.

"Because so far, we have not advanced past the stage at which we found ourselves in June" in Moscow.

"We have lost a lot of time," Russia's top nuclear negotiator said.

"We do not think you can lose time anymore."

Talks between Iran and the so-called P5+1 powers -- the five permanent UN Security Council members and Germany -- have been held on three occasions at the highest level in the past year.

None of the meetings has drawn a promise from Tehran to scale back its controversial nuclear enrichment programme to levels that world powers believe cannot be used to make atomic weapons.

Iran denies its nuclear programme has a military component and insists on global recognition of its right to enrich uranium for peaceful purposes.

World powers counter that Iran sacrificed its enrichment rights by refusing to cooperation with international nuclear inspectors.

The dispute has resulted in four rounds of global sanctions against Tehran -- in addition to unilateral US and EU measures -- that have crippled the Iranian economy and hit its oil exports.