The UN atomic watchdog and Iran said Wednesday that they aimed to agree next month additional "practical steps" to increase transparency over Tehran's nuclear programme.

International Atomic Energy Agency chief inspector Tero Varjoranta said after talks in Vienna that the January 21 meeting would also cover long-standing allegations of nuclear bomb research by Tehran.

"We aim to reach agreement on what those practical measures are in our next technical meeting, which is scheduled for January 21 in Tehran," Varjoranta told reporters.

On November 11 Iran and the IAEA agreed a framework deal that included six practical steps that Tehran would take within three months -- by February 11.

The first, a trip to a plant producing so-called heavy water for a reactor under construction at Arak, took place on December 8 when all of the IAEA's "technical objectives" were met, Varjoranta said.

The second, a visit to the Gachin uranium mine in southern Iran, has yet to be arranged but would take place before February 11, Varjoranta said.

Others include providing information on all new research reactors, on 16 sites designated for nuclear power plants, on additional uranium enrichment facilities and on laser enrichment technology.

Reza Najafi, Iran's ambassador to the IAEA, said Wednesday's meeting was "very good" and that it touched on new "practical measures" to be taken in the "next phase after February 11".

The November 11 agreement did not specifically mention the IAEA's stalled two-year effort to get answers from Iran over the allegations that prior to 2003, and possibly since, Iran's nuclear programme had "military dimensions".

The deal said only that Iran and the IAEA "will cooperate further with respect to verification activities to be undertaken by the IAEA to resolve all present and past issues".

Iran denies seeking or ever having sought nuclear weapons. It says that the IAEA's allegations, set out in a major report in November 2011, are baseless.

Some of the measures tally with a landmark deal agreed by Iran and world powers in Geneva on November 24 on Iran rolling back its nuclear programme for six months in exchange for modest sanctions relief.

Talks between experts from Iran and the United States, China, Russia, Britain, France and Germany -- the P5+1 -- and the IAEA on implementing that deal continued for a third day in Vienna on Wednesday.