Nackaerts said on Thursday that the IAEA is committed to continue talks with Iran on the country's nuclear program.
Speaking to reporters at Vienna airport after returning from Tehran, he said during talks with Iranian officials the two sides exchanged views on Modality plan but they did not reach any final agreement to this end.
The date for next round of talks between the two sides has not being set yet, he said.
The International Atomic Energy Agency team, headed by Herman Nackaerts, arrived in the Iranian capital, Tehran, in the early hours of Wednesday.
The IAEA experts discussed issues pertaining to Tehran's nuclear energy program with Iranian officials.
Iran's Ambassador to the IAEA Ali Asqar Soltaniyeh headed the Iranian negotiating team.
Nackaerts said on Tuesday before leaving Vienna for Tehran that the IAEA's objective was to "finalize the structured approach document" in view of resolving the remaining issues regarding Iran's nuclear activities.
"We will have good negotiations," he stated.
Iran, too, announced that it is prepared to reach a comprehensive agreement with the International Atomic Energy Agency based on the recognition of its nuclear rights.
"We are ready to reach a comprehensive agreement with the IAEA on the basis of which our country's nuclear rights will be fully recognized in accordance with the NPT (Non-Proliferation Treaty)," Iranian Foreign Ministry Spokesman Ramin Mehman-Parast said in his weekly press conference in Tehran on Tuesday.
