PARIS - Iranian President-elect Hassan Rowhani personally stopped the development of a clandestine nuclear weapon in 2003, a former ambassador to the country said Saturday.

Writing in the International Herald Tribune newspaper, Francois Nicoullaud, France’s ambassador to Iran from 2001 to 2005, said he believed Rowhani was the “main actor” in persuading the country’s Supreme Leader Ali Khamenei to halt the secret programme.

Rowhani, who led the nuclear negotiating team under reformist former president Mohammad Khatami from 2003-2005, will take power on August 3 after his election on June 15.

“Based on conversations that I had at the time, as French ambassador to Tehran, with high Iranian officials close to the matter, I firmly believe that Rowhani was the main actor in the process,” Nicoullaud wrote. “Of course, Iranians could not admit to a foreigner that such a program ever existed, and I cannot name the officials I spoke to.”

Nicoullaud went on to describe a meeting with a “high-ranking official” after Iran had agreed with Western powers to suspend enrichment in October 2003.

After this agreement, the official “confided to me that ... Rowhani issued a general circular asking all Iranian departments and agencies, civilian and military, to report in detail about their past and ongoing nuclear activities.

“The official explained to me that the main difficulty Rowhani and his team were encountering was learning exactly what was happening in a system as secretive as Iran’s.

“A few weeks after, I heard from another official, a close friend of Rowhani: ‘The Rowhani team is having a hard time ... People resist their instructions ... But they will prevail’.”

After Nicoullaud advised the official to give researchers more time to archive their work, his source later replied: “I conveyed your message ... It worked!”

The retired diplomat confirmed to AFP Saturday he now believes that the project Rowhani’s team was working on was the Revolutionary Guard programme.

“Uranium enrichment was the visible part of it but there was a hidden section, the manufacture of a nuclear device — once they had produced enriched uranium, how to put it on the head of a missile and how to deliver it to ‘friends’ in the region — that’s the programme Rowhani stopped,” the former ambassador said.

“I had known for a long time but now that Rowhani is becoming president I had enough consistent information to prove that he was the principal figure, who made his decision known to the Supreme Leader,” Nicoullaud said.

“Above all it was put into action, forcing the Revolutionary Guards to halt the programme that they held so very dearly,” added the former diplomat.