Visiting chief of UN nuclear watchdog Yukiya Amano has reached agreement with top Iranian officials on the timetable for cooperation to solve existing problems, Iranian Ambassador to the International Atomic Energy Agency (IAEA) Reza Najafi has said.

The talks were held in an interactive atmosphere which helped "to reach an agreement on the timetable for cooperation to solve the existing problems considering the concerns of both sides," Najafi was quoted as saying by official IRNA news agency here on Thursday.

"Coordination will be made soon to decide on the details and the timetable (of the cooperation) at the expert level," he added.

Amano arrived in Tehran on Thursday to discuss mechanisms for clarification of key nuclear issues with top Iranian officials.

He met Iranian President Hassan Rouhani and Ali Shamkhani, who heads Iran's Supreme National Security Council.

In June, Amano said that the progress on the clarification of the so-called possible military dimensions of Iran's nuclear plan was still slow and it might take years to resolve the issue.

Iran denied the allegation, saying the information was forged and misleading.