TEHRAN, July 1 -- Head of the UN nuclear watchdog, Yukiya Amano, will visit Iran's capital Tehran on Thursday to discuss mechanisms for clarification of outstanding nuclear issues with top Iranian officials, IRNA news agency reported on Wednesday.

Amano will meet Iranian President Hassan Rouhani and Secretary of Iran's Supreme National Security Council Ali Shamkhani to seek Iran's suggestions to resolve the remaining issues regarding Tehran's alleged nuclear weapon program.

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

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

The IAEA chief's visit comes after missing the self-imposed June 30 deadline for a comprehensive deal between Iran and the world's major powers over the former's controversial nuclear program. On Tuesday, both sides agreed to extend the deadline for another week.

Iran and five United Nations Security Council permanent members plus Germany (P5+1) are seeking a long-term solution to the disputed Iranian nuclear issue.

Under a possible deal, the International Atomic Energy Agency (IAEA) will be tasked to monitor Iran's nuclear activities and to verify whether they are peaceful.