Iran and world powers on Tuesday broke a deadlock over the date and venue of stalled negotiations on Tehran's disputed nuclear ambitions, agreeing to meet in Kazakhstan later this month.

The agreement was made in a telephone conversation between the offices of Iran's top nuclear negotiator Saeed Jalili and European Union foreign policy chief Catherine Ashton, the official IRNA news agency reported.

Ashton's office confirmed the contact in which, it said, the Kazakh city of Almaty was selected for the resumption of the talks on February 26.

"She hopes that the talks will be productive and that concrete progress can be made towards a negotiated solution to meet the international community's concerns about the Iranian nuclear programme," her office said in a statement.

The talks aim to address a key Western concern about Iran's capacity to enrich uranium to fissile purities of 20 percent, a process that can be used for peaceful atomic purposes as well as for making the core of a nuclear bomb.

Ashton represents the so-called P5+1 group of the United States, Russia, China, Britain and France plus Germany, which held three rounds of talks with Iran last year.

France and the United States warned Monday that they would step up pressure on Iran in the upcoming talks.

"Despite all efforts, Iran is still refusing to be transparent," French President Francois Hollande told a joint news conference with US Vice President Joe Biden.

"Therefore we will pressure it right to the end to ensure the negotiations succeed," he added.

The last of such efforts ended in a stalemate in Moscow eight months ago, when Iran refused Western demands to curb its activities and asked for a substantial sanctions relief.

The news came after Iranian Foreign Minister Ali Akbar Salehi had flagged February 25 as the date for the talks, which were initially expected in December but postponed due to uncertainty over final agreements.

Western powers suspect Iran is disguising military objectives within a civilian atomic programme. Tehran vehemently denies the charges, insisting its activities are peaceful.

The IRNA report on Tuesday did not make any allusion to the offer of direct talks with Washington, mooted by Biden, over the nuclear issue.

"We have made it clear at the outset that... we would be prepared to meet bilaterally with the Iranian leadership," Biden told the Munich Security Conference last week.

"That offer stands, but it must be real and tangible, and there has to be an agenda that they're prepared to speak to. We are not just prepared to do it for the exercise."

At the time, Salehi reacted by saying Iran was open to the US offer for if Washington's intentions were "authentic," without giving any commitments.

Decisions on the nuclear programme rest with Iran's supreme leader, Ayatollah Ali Khamenei, whose representative Jalili at Iran's Supreme National Security Council handles talks with world powers.

Khamenei has the final say on all key state issues.

Iran has been slapped by multiple sets of UN Security Council sanctions for its refusal to stop uranium enrichment. The United States and the European Union have also imposed additional sanctions on Iran.

Tehran is also locked in a showdown with the UN's atomic watchdog agency, which is hoping to gain broader access to its nuclear facilities in a bid to find a way forward to resolve outstanding issues of Iran's past atomic activities.

Israel, the Middle East's sole if undeclared nuclear weapons state, has refused to rule out military intervention to prevent Iran from reaching military atomic capabilities.

And Israeli President Shimon Peres on Tuesday told parliament the threat of a nuclear-armed Iran was growing under the "terrifying dictatorship" ruling the Islamic republic.