TEHRAN, Iran -- Iran's President Hassan Rouhani on Sunday told the visiting head of the U.N. nuclear agency that Tehran has never pursued nuclear weapons and that inspectors should be "fair" when they help implement a landmark nuclear deal reached with world powers in July.

Yukiya Amano, the head of the International Atomic Energy Agency, arrived in Tehran earlier in the day on his second visit in the past three months, ahead of an Oct. 15 deadline to gather information on allegations that Iran had in the past tried to build atomic weapons. A final U.N. assessment is due in December.

Western nations have long suspected Iran's nuclear program has a secret military dimension. Iran denies the charge, saying the program is entirely devoted to peaceful purposes like power generation and cancer treatment.

"Under the deal, we will voluntarily carry the Additional Protocol and we hope you have fair observation on implementation of the deal," Rouhani told Amano. The Additional Protocol provides for expanded IAEA safeguards, including snap inspections of nuclear sites.

Rouhani reiterated that Iran has had "no diversion from its peaceful nuclear program," saying the program's purely civilian nature had been verified through years of IAEA monitoring and snap inspections.

Amano said Sunday that his agency's work in Iran and elsewhere is "based on impartiality." He later told a special parliamentary committee that the agency will keep information on Iran's nuclear program confidential, the official IRNA news agency reported.

In the past, Iran has accused the U.N. agency of leaking information about its nuclear program to Western nations and Israel, posing a threat to Tehran's nuclear facilities and scientists.

Amano said the agency expects to wrap up remaining issues with Iran "by the end of the current year."

Iran's Foreign Minister Mohammad Javad Zarif meanwhile expressed hope that the United States would uphold its end of the deal, which provides for billions of dollars in sanctions relief in exchange for Iran curbing its nuclear activities.

Speaking at a press conference with his Dutch counterpart, Bert Koenders, Zarif said that if Washington fulfills its obligations it would help to "make up for the mistrust that has been created over the past decades and show a new kind of approach toward the Islamic Republic of Iran."