Iran agreed on "some points" in talks with UN atomic experts in Tehran on Wednesday, two weeks ahead of negotiations with world powers aimed at finding a diplomatic solution to end a standoff over its nuclear ambitions.
"Some differences were resolved and agreement on some issues in the modality was reached," Ali Asghar Soltanieh, Iran's envoy to the International Atomic Energy Agency (IAEA), was quoted as saying by the ISNA news agency.
"New proposals," Soltanieh said, had been put forward in the meeting but they would be discussed at "future meetings."
He did not say if a date had been agreed for the resumption of talks with the IAEA, whose chief inspector Herman Nackaerts led its delegation to Tehran.
Nackaerts had hoped that in Tehran, the IAEA would "finalise the structured approach document" which would allow a probe into a possible military dimension of Iran's nuclear drive.
The Vienna-based agency says "overall, credible" evidence exist that until 2003 and possibly since Iran conducted nuclear weapons research, despite repeated denials from Tehran.
The IAEA is also pressuring Tehran to grant it access to Parchin, a military base near Tehran where the agency suspects Iran could have carried out experiments with explosives capable of triggering a nuclear weapon.
Those calls have been spurned by Tehran, which says it should first reach a final agreement with the IAEA before such visit is debated.
Wednesday's discussions took place as the P5+1 group of the United States, Russia, China, Britain, France and Germany are gearing for parallel diplomatic efforts to persuade Iran to curb parts of its nuclear drive.
The six are to meet Iranian negotiators in the Kazakh city of Almaty on February 26, after an eight-month hiatus and failed meetings in Istanbul, Baghdad and Moscow.
European Union foreign policy chief Catherine Ashton, who coordinates efforts with the P5+1, said on Wednesday she hoped Iran would show some "flexibility" at the upcoming talks.
Signup to our newsletter and follow us on Facebook and Twitter!
"We hope that Iran will come to these negotiations with flexibility, and that we can make substantial progress," Ashton told the UN Security Council.
"We remain determined to work towards a solution to the Iran nuclear issue based on the dual-track approach," combining sanctions and dialogue, she said.
The West and Israel suspect the Islamic republic is masking the development of a nuclear weapons capability under the guise of a programme Iran insists is purely aimed at peaceful purposes.
Iran is already slapped with multiple sets of Security Council sanctions for its refusal to stop uranium enrichment, a process that can be used for peaceful atomic purposes as well as for making the core of a nuclear bomb.
The United States and the European Union have also imposed their own separate sanctions to choke off Iran's revenue from its vital oil exports -- a measure exacerbating Iran's struggling economy and rising inflation.
In November, the US warned that if there was no progress in a deal between Iran and the IAEA, it would push for the UN agency to take the rare step of referring Tehran to the UN Security Council.
On Wednesday, as the talks with the IAEA were underway, Iran announced it was upgrading its uranium enrichment machines.
Atomic Energy Organisation chief Fereydoon Abbasi Davani said new centrifuges with "a higher efficiency" were being installed at Iran's Natanz site, which uses the machines to enrich uranium gas by spinning it at supersonic speeds.
The P5+1 have pressured Iran to address a key Western concern about its capacity to enrich uranium to fissile purities of 20 percent, demanding that Tehran abandons this part of its programme.
Rebuffing the calls, however, Iran is instead asking for a substantial sanctions relief in return.
Decisions on nuclear work rest with the Islamic republic's supreme leader Ayatollah Ali Khamenei, whose representative Saeed Jalili leads the negotiating team in the talks with world powers.