A moderate think tank led by Iran's former top nuclear negotiator accused President Mahmoud Ahmadinejad of distorting facts about the country's nuclear program to depict himself as a hero and improve his chances in the upcoming election. It is rare for an Iranian think tank to criticize the president in such a direct manner, indicating the high stakes ahead of the June 12 election. Ahmadinejad faces a tough battle against reformists who have criticized him for spending too much time slamming the West instead of improving Iran's faltering economy. The president has attempted to deflect the blame by playing up Iran's nuclear achievements during his time in office. But the Center for Strategic Research, led by former nuclear negotiator Hasan Rowhani, said Ahmadinejad has attempted to downplay the role of his predecessors in developing Iran's nuclear program, which was started in the 1980s under former Prime Minister Mir Hossein Mousavi, the president's leading election challenger. It also accused Ahmadinejad of exaggerating his role in standing up to the West over a 2003 deal his reformist predecessor, Mohammad Khatami, reached with three European countries to temporarily suspend Iran's uranium enrichment program. Ahmadinejad has called the deal, which was negotiated by Rowhani, "disgraceful" and said he restored Iran's dignity by resuming the country's enrichment program after he took office in 2005. But the think tank noted that Khatami actually reversed the freeze shortly before Ahmadinejad took office in response to international demands to permanently suspend the nuclear program. "It's deploring that some historical facts have deliberately been distorted in the past four years," the group said in a statement issued Friday. The 2003 deal with Britain, France and Germany was aimed at easing Western fears that Iran was seeking to build nuclear weapons - a charge that Tehran has denied. The think tank said Iran's Supreme Leader Ayatollah Ali Khamenei approved the deal, which it said was "wise" because it was temporary and saved Iran from UN punishment. In contrast, the group said Ahmadinejad's hard-line policy has prompted the UN to impose three rounds of financial sanctions on Iran for failing to suspend uranium enrichment - a process that can produce fuel for a nuclear reactor or material for a bomb. Iran first began enriching uranium under Ahmadinejad's leadership in Feb. 2006 and produced nuclear fuel for the first time in April of that year. The think tank said Ahmadinejad's decision to dismiss the U.N. sanctions as "worthless" and "torn bits of paper" has only brought greater harm to Iran. Rowhani has invited Ahmadinejad to debate Iran's nuclear policy, but the president has not yet responded.