The International Atomic Energy Agency (IAEA) said Wednesday that another meeting between the UN nuclear watchdog and Iran over its nuclear programme will take place in Tehran from February 21 to 22.

"The Agency is committed to intensifying dialogue. It remains essential to make progress on substantive issues," IAEA chief Yukiya Amano said in a statement.

The announcement came after a high-ranking IAEA delegation returned to the agency's headquarters in Vienna following a trip to Iran.

"The IAEA explained its concerns and identified its priorities, which focus on the clarification of possible military dimensions to Iran's nuclear programme," Amano said.

During the newly-concluded talks, the IAEA also discussed with Iran the topics and initial steps to be taken, as well as associated modalities, he added.

The spirit dominating the three-day talks between Iranian officials and the IAEA team was "positive and constructive", Iran's official IRNA news agency said Tuesday, quoting an unnamed source.

The report also said the IAEA delegation, headed by chief inspector Herman Nackaerts, did not visit or inspect any nuclear site in Iran.

The talks were held behind closed doors and no details about its process or outcome were released.

Last November, the board of the IAEA adopted a resolution on Iran's nuclear program suspected of having weapons-related activities, and called for intensified dialogue to find solutions to unresolved issues.

However, Iran has said the resolution will not stop its nuclear program which it insists is peaceful in nature despite the West's accusation of military purposes.