The chief UN nuclear inspector said Friday after "good" talks in Tehran that he expects to reach a deal with Iran in January on outstanding issues over its controversial atomic programme.

"We have agreed to meet again on 16 January next year, where we expect to finalise the structured approach and start implementing it then shortly after that," Herman Nackaerts of the International Atomic Energy Agency said.

"We had good meetings," he told reporters at Vienna airport after the meeting in Tehran, adding that Parchin, a military base at the centre of the IAEA's investigation is "part of the structured approach."

Meanwhile, local Iranian news outlets said on Thursday confirmed the progress in the negotiating process, as Tehran's IAEA Ambassador to the UN atomic watchdog Ali Asghar Soltanieh described the talks as "productive and developing".

Parchin featured in a major IAEA report issued in November 2011 summarising what it says is "overall, credible" evidence that until 2003, and possibly since, Iran conducted weapons research.

Because the bulk of the information in the report comes from foreign intelligence agencies, Iran has said it is either forged or related to non-nuclear work.

The IAEA has zeroed in on Parchin because some of its information on the base is "independent".

Thursday's meeting between Nackaerts's team and Iranian officials was the latest in a string of what have up till now been fruitless talks this year between the Iranians and the IAEA, the latest in August in Vienna.

The IAEA says it is seeking to reach agreement with Iran on a "structured approach" to resolve outstanding concerns and to obtain its inspectors broader access to Iran's nuclear sites and people working in the programme.

Iranian Foreign Ministry spokesman Ramin Mehmanparast said Tuesday the visit would focus on discussions regarding "Iran's nuclear rights as well as its peaceful nuclear activities."

But "certain issues that have possibly become a source of concern for (IAEA) officials can also be discussed," he said, without being specific.

Subject to international sanctions, Iran rejects as baseless suspicions by Western governments, echoed by the IAEA, that it intends to develop nuclear weapons capability under the guise of its energy programme.

Tehran earlier said that IAEA's demands to examine Parchin exceed Iran's obligations under the Nuclear Non-Proliferation Treaty (NPT), to which it is a signatory.

The United States has warned that it will push for the board of the Vienna-based agency to refer Iran to the UN Security Council if Tehran displays no "substantive cooperation" by March.

The West suspects Iran is using its nuclear programme as a cover for developing atomic weapons, charges Tehran denies.