UN chief Ban Ki-moon met Iran's president and supreme leader in Tehran on Wednesday and urged them to take concrete steps to prove the country's nuclear program is peaceful.He also called on all states to stop supplying arms to the conflict in Syria, Ban's spokesman, Martin Nesirky, said.UN nuclear watchdog sets up 'Iran Task Force'Meanwhile Wednesday, an internal IAEA document showed that the United Nations' nuclear watchdog had set up an Iran Task Force to handle inspections and other issues related to the Islamic state's disputed atomic activities.The brief announcement by the International Atomic Energy Agency, addressed to agency staff, appeared to be an attempt to focus and streamline the IAEA's handling of the sensitive Iran file by concentrating experts and other resources in one unit.The Vienna-based UN agency, which regularly inspects Iran's nuclear sites, has voiced growing concern over the last year of possible military dimensions to the country's nuclear program. Tehran says its nuclear work is entirely peaceful.A new report to be circulated to IAEA member states later this week is expected to say that Iran has installed 350 new centrifuges in its underground Fordow facility since May, AFP quoted Vienna-based diplomats as saying on Wednesday.Iran is enriching uranium to a fissile concentration of 20 percent -- easily upgraded to the 90 percent needed for bombs -- at Fordow, buried deep inside a mountain near the holy Shi’ite city of Qom to protect it from foreign attack. The Vienna diplomats also expect the report to chastise Iran over sanitizing its military base at Parchin.The ongoing sanitization efforts, meant to eliminate evidence of possible nuclear work at the site, may make inspections "pointless," according to the diplomats.Iran indicated on Monday it might allow diplomats visiting Tehran for this week's Non-Aligned Movement (NAM) summit to inspect the Parchin military base, which UN nuclear experts say may have been used for nuclear-related explosives tests.When asked about the possibility, Iranian Deputy Foreign Minister Mohammad Mehdi Akhoundzadeh said: "Such a visit is not customary in such meetings.... However at the discretion of authorities, Iran would be ready for such a visit," the Iranian government-linked news agency Young Journalists Club reported.Any visit to Parchin by NAM representatives would do little to calm Western concerns or those of the IAEA whose talks with the Iranians ended on Friday without agreement.The UN body suspects that Iran has conducted explosives tests in a steel chamber at Parchin relevant for the development of nuclear weapons, possibly a decade ago.Last week diplomatic sources said Iran had covered the building believed to house the explosives chamber with a tent-like structure, fueling suspicions about a clean-up there.Iran says Parchin, a vast, sprawling complex southeast of Tehran, is a conventional military facility and has dismissed allegations about it as "ridiculous."He told reporters in New York that in separate meetings with President Mahmoud Ahmadinejad and Supreme Leader Ayatollah Ali Khamenei, the secretary-general further said that he considered their latest verbal attacks on Israel to be offensive, inflammatory and unacceptable.Ban arrived in Tehran on Wednesday for a three-day visit to attend a meeting of some 120 non-aligned nations. He defied calls from the United States and Israel to boycott the event."On the nuclear question ... he said that he regretted that little tangible progress has been achieved so far," Nesirky, speaking by telephone from Tehran, told reporters in New York."He said that Iran needed to take concrete steps to address the concerns of the International Atomic Energy Agency and prove to the world that its nuclear program is for peaceful purposes," Nesirky said.Iran says its program is peaceful, but Western powers and their allies fear it is aimed at developing atomic weapons. Iran has been hit with four rounds of UN Security Council sanctions for refusing to halt its nuclear enrichment program.On Syria, Ban urged Iran's leaders to use their influence to call on Syria's President Bashar Assad to end the violence and create conditions for "credible dialogue and a genuine political process that meets the will of the Syrian people.""The secretary-general reiterated his opposition to the further militarization of the conflict and called on all states to stop supplying arms to all sides in Syria," Nesirky said.Last week the United Nations said Iran appears to be supplying Syria with weapons, as the 17-month conflict that began as a popular uprising against Assad slides deeper into civil war.Ban expressed concern about the human rights situation in Iran and also said that he strongly objected to recent remarks by Iran's leaders on Israel.Earlier this month Ahmadinejad said there was no place for the Jewish state in a future Middle East and Khamenei said Israel would one day be returned to the Palestinian nation and would cease to exist."He said such offensive and inflammatory statements were unacceptable and should be condemned by all," Nesirky said.