PARIS (Reuters) - France's main negotiator in talks between six world powers and Iran is leaving his post at a crucial moment, less than two months before the deadline for a final agreement over Tehran's nuclear programme.
Jacques Audibert, who has pushed for a tough line on Iran, has been promoted to a senior role in President Francois Hollande's diplomatic team, the president's office said on Thursday.
Paris has long held out for strict terms in the talks, in which the United States, Russia, China, Britain, Germany and France are contemplating a further easing of economic sanctions if Iran can dispel their concerns that it wants to build nuclear weapons - an intention it strongly denies.
Under Audibert, that stance has toughened. With concerns rising among Iran's foes, especially Israel and the Gulf states, that the United States has turned softer on Iran, France has become a key player in defending their interests.
In 2011, it successfully pushed for a European Union oil embargo and stricter controls over Iran's central bank.
After marathon negotiations in November to reach an interim deal with Iran, Audibert, concerned the agreement was still too weak, called in his foreign minister to join the talks. The accord was eventually strengthened, enabling a breakthrough preliminary agreement that took effect on Jan. 20.
Under the deal, Iran halted some aspects of its nuclear programme in exchange for a limited easing of international sanctions that have laid low the major oil producer's economy.
The sides had intended to start drafting a final agreement earlier this month that could end more than a decade of enmity and mistrust. But they made little progress, raising doubts over the prospects for a breakthrough by the July 20 deadline.
They are due to meet again at some point in June.
Audibert's departure also comes as EU foreign policy chief Catherine Ashton, who has been the prime coordinator of the negotiations since 2010, prepares to step down in October.
Any delay beyond July could fuel more uncertainty as new negotiation teams are put in place.
Audibert, a former radio journalist, has been director general for political and security affairs at the French foreign ministry since 2009. His replacement has yet to be named.
Reporting by John Irish and Elizabeth Pineau; Editing by Mark Trevelyan