Announcing nuclear deal in Moscow
As Iran came under increasing Western pressure during 2003 over its nuclear programme, Hassan Rowhani emerged as the country's chief negotiator.
Mr Rowhani's official post is secretary of the Supreme National Security Council (SNSC), a body set up in 1989 to "safeguard national interests and protect the Islamic Revolution".
He represents Iran's supreme leader, Ali Khamenei, on the SNSC, which is chaired by the President, Mohammad Khatami.
He was confirmed in the post for a further three years in May 2004.
Analysts believe Ayatollah Khamenei picked Mr Rowhani, rather than a government minister or the reformist president, for the nuclear job because of his closeness to the hardline clergy, which would make him more acceptable to the military.
Born in 1948, Mr Rowhani studied theology in the holy city of Qom. He went on to gain a doctorate in law.
According to the conservative Jomhuri-ye Eslami daily, he was active from an early age in the movement to overthrow the Shah and was twice arrested, in 1964 and 1977.
Among his previous posts the paper lists: member of the military leadership during the Iran-Iraq war of 1980-1988, head of the Air Defence Centre, and head of a prison.
Mr Rowhani is currently a director of Iran's Centre for Strategic Studies and a member of the Assembly of Experts, which has the power to elect and remove the supreme leader.
He is often described by Western sources as a "moderate" or "pragmatic conservative". He is considered close both to the supreme leader and to the former President, Akbar Hashemi Rafsanjani, who now heads the influential Expediency Council.
Mr Rowhani was deputy speaker of the Iranian parliament, or Majlis, during the student riots of July 1999.
He told a rally in Tehran at the time that those arrested for sabotage and destroying state property during the student unrest would face the death penalty if found guilty.
In July 2001 he visited Georgia, Armenia and Azerbaijan, with the stated aim of promoting security and stability in the strife-riven region.
Two years later he shot to prominence in a very different diplomatic arena.
In June 2003 it was Mr Rowhani who told visiting British Foreign Secretary Jack Straw that the head of the UN nuclear watchdog, the IAEA, would be invited back to clear up obstacles to Iranian compliance with key Western demands.
Then, on a visit to Moscow in November 2003, he said Iran was suspending uranium enrichment and would allow tougher UN inspections. He said the move was intended to "eliminate all concerns and fears".
The announcement, which followed talks in October with the foreign ministers of Britain, Germany and France, was welcomed by the Europeans, but greeted with scepticism by the United States.
While widely credited with achieving a "breakthrough" over the nuclear issue, Mr Rowhani has insisted that Tehran will resist US pressure for further concessions.
"We have said clearly that any phrase in a resolution aimed at transforming the voluntary pledge by Iran to suspend uranium enrichment into a legal obligation will be unacceptable to us," he was quoted as saying by state radio and the official news agency.
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