Iranian President Mahmoud Ahmadinejad has appointed a new head for the Islamic republic's nuclear program, following the abrupt resignation of its veteran chief, the official IRNA news agency reported Friday. Ali Akbar Salehi, Iran's former envoy to the International Atomic Energy Agency, replaces Gholam Reza Aghazadeh as the new vice president and the head of the Atomic Energy Organization of Iran, IRNA said. Although officials gave no reason for Aghazadeh's resignation, he has long been close to reformist opposition leader Mir Hossein Mousavi, who claims to be the victor in June 12 presidential elections and has called Ahmadinejad's government illegitimate. The replacement is unlikely to bring any change in the nuclear policy or impact the standoff between Iran and the West over the country's nuclear program since head of the nuclear program is not directly involved in negotiations, and ultimately all decisions on policy lie with Supreme Leader Ayatollah Ali Khamenei. Salehi most high profile moment came in 2003 when 18 years of Iran's clandestine nuclear activities were exposed, putting Iran's nuclear issue at the top of the IAEA Board of Governors agenda. In December 2003, Salehi signed an additional protocol to the Nuclear Nonproliferation Treaty under former reformist president Mohammad Khatami that enabled IAEA inspectors to search Iranian nuclear facilities without notice and without restriction. Ahmadinejad later stopped the intrusive inspections in protest of the Iran's referral to the UN Security Council that subsequently imposed sanctions against the country for refusing to halt its controversial uranium enrichment program. Salehi holds a doctorate in nuclear physics from the Massachusetts Institute of Technology in the United States. He was also associate professor and chancellor of Sharif University of Technology in Teheran. His predecessor Aghazadeh is widely respected in Iran as a father of the nation's nuclear program. In his 12 years on the job, Aghazadeh pushed steadily ahead with the nuclear program, which the West fears is aimed at developing a weapon. Iran denies that charge. In the past year, he announced several advances in manufacturing centrifuges, a key component of the enrichment program. According to the UN nuclear watchdog, Iran has nearly 5,000 centrifuges currently enriching uranium for use as a nuclear fuel and another 2,000 others ready to begin. Aghazadeh has made no public comment on the June 12 election turmoil, in which Mousavi supporters staged massive street demonstrations before the government crushed them in a heavy crackdown, but he is known close associate of Mousavi ever since the opposition leader was the prime minister in the 1980s. The outgoing nuclear chief is also close to Akbar Hashemi Rafsanjani, a powerful cleric and former president who is a bitter rival of the president. Aghazadeh was among a group of pro-Rafsanjani officials who formed a political party, Kargozaran, in the early 1990s. There have also been hints of behind-the-scenes differences between Aghazadeh and Ahmadinejad's energy minister over the planned opening of Iran's first nuclear plan at Bushehr, whose opening has repeatedly been delayed.