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Iran's former nuclear negotiator accused hard-line President Mahmoud Ahmadinejad of distorting facts about the country's nuclear past to make himself look like a hero and win votes in next week's election.

Hasan Rowhani, who negotiated a 2003 deal with Europe to suspend Iran's controversial uranium enrichment program, also called Ahmadinejad a "demagogue" for claiming his administration was behind all of Iran's nuclear success.

In comments posted Friday on a Web site belonging to Rowhani's think tank, The Center for Strategic Research, the ex-negotiator said Ahmadinejad's hard-line policies harmed Iran's reputation and led to three rounds of U.N. sanctions against Iran.

"Is it dignity that economic sanctions are imposed against Iran?" Rowhani asked.

The criticism is part of the verbal dueling before the June 12 presidential election, in which Ahmadinejad faces a tough challenge from three other contenders, including two reformists who favor better ties with the West.

Using language similar to Rowhani's, the president's main challenger, pro-reform candidate Mir Hossein Mousavi, accused Ahmadinejad of driving Iran toward "dictatorship" in an election debate on Wednesday.

Ahmadinejad said reformists humiliated Iran because they halted all the nuclear work under the 2003 deal.

The reformists say this is not true and that only uranium enrichment was stopped. They say it was a temporary step that saved Iran from U.N. punishment, while allowing it to continue to develop other parts of its nuclear program.

"Unfortunately, some of the president's statements are so ridiculous and baseless that they don't deserve a response," Rowhani said.

Ahmadinejad's campaign has touted Iran's nuclear progress in efforts to deflect criticism of his handling of the country's economy, something his opponents have honed in on.

Rowhani is a moderate with close ties to former President Hashemi Rafsanjani, a top cleric who held the presidency from 1989-97.

Ahmadinejad recently denounced the 2003 deal under his predecessor, Mohammad Khatami, as "disgraceful."

After coming to power in 2005, Ahmadinejad resumed uranium enrichment, which the U.S. and its allies fear Iran intends to use to make nuclear arms — a charge Tehran denies. Uranium enrichment can produce fuel for nuclear power plants or material for a bomb.

"I don't know why the gentleman insists on distorting facts ... for the sake of obtaining a few more votes" or making himself look like a hero, Rowhani said, referring to Ahmadinejad.

"Harsh words won't help win votes," he added. "Demagoguery no longer works."

Rowhani defended the 2003 suspension as "wise" because it came amid intense pressure by the U.N. nuclear watchdog agency and fears that Washington could move against Tehran after toppling the extremist Taliban regime in Afghanistan and former Iraqi dictator Saddam Hussein.

Khatami, who ran the country between 1997-2005, has already demanded an apology from Ahmadinejad for calling the 2003 deal disgraceful and for saying Khatami played into "colonial policies" designed by Iran's enemies bent on "finishing" the Iranian nation.

Khatami and Rafsanjani are not running in the election, but their criticism of Ahmadinejad has added to the president's troubles during the campaign.

Ahmadinejad's chief reformist rivals are: Mousavi, a former prime minister in 80s, and Mahdi Karroubi, a former parliamentary speaker. The sole conservative challenger to Ahmadinejad is Mohsen Rezaei, a former Revolutionary Guards commander.