By Jonathan Allen and John Irish
VIENNA (Reuters) - Iranian Foreign Minister Mohammad Javad Zarif will leave the nuclear talks with six world powers on Friday and return to Tehran for top level discussions four days before a deadline for a final agreement expires.
U.S. Secretary of State John Kerry and French Foreign Minister Laurent Fabius will also return to Paris later on Friday for consultations on the Iranian nuclear issue, U.S. and French officials said.
"Zarif will return to Tehran tonight for consultations and exchange of views with top officials," Iran's official news agency IRNA reported, citing a member of the Iranian delegation at the Vienna talks.
The United States, Britain, France, Germany, Russia and China began the final round of negotiations with Iran on Tuesday before Monday's deadline, looking to secure a settlement to the decade-old dispute and put a cap on Tehran's nuclear ambitions.
However, officials close to the talks say the two sides are unlikely to secure a definitive accord and may need to extend the deadline.
One source close to the talks told Reuters Zarif would discuss a proposal he received from the six that outlines the main principles of a possible agreement on removing sanctions on Tehran in exchange for curbs on its nuclear program.
The West believes Iran wants to develop nuclear weapons -- a suggestion Tehran rejects.
Western diplomats told Reuters earlier this week that a U.S.-drafted proposal shown to Iran at talks in Oman earlier this month called for the Islamic Republic to reduce the number of its uranium enrichment centrifuges to 4,500, well below the current number of centrifuges Tehran has.
Iran has roughly 19,000 centrifuges installed and about 10,000 in operation. Iranian officials say they refuse to reduce the volume of uranium they are capable of enriching, which Western officials say is unacceptable. That is a major sticking point in the talks.
Another sticking point is the lifting of sanctions. Iran wants them terminated swiftly, not suspended and later terminated as Western powers are calling for.
Western and Iranian diplomats in Vienna told Reuters that Zarif was expected to return to Austria during the weekend.
It was not clear when Kerry will be back in Vienna. State Department spokesman Jen Psaki said he was leaving "for consultations with his European counterparts about the ongoing Iranian nuclear negotiations".
"He will also stay in close touch with his inter-agency colleagues in Washington," Psaki said. "His future travel schedule is still being finalized, and we have not yet determined when he will return to Vienna."
French officials said Fabius would head back to Paris later on Friday and was also set to return over the weekend.
Zarif, Kerry and Fabius were holding a series of different meetings in Vienna on Friday with European Union envoy Catherine Ashton and British Foreign Secretary Philip Hammond.
"We have to get more flexibility from the Iranians," Hammond told reporters upon arrival. "In return we are prepared to show some flexibility on our side. But time is short, we are up against a deadline here."
Hammond also said Iran and the six world powers have "a long way to go" to get a final agreement.
Western diplomats said Iran has so far shown no flexibility and all the compromise proposals have come from the six. Iran rejects allegations by Western officials and their allies that it is amassing the capability to produce atomic weapons.
(Reporting by Parisa Hafezi, Louis Charbonneau and Fredrik Dahl; writing by Louis Charbonneau; Editing by Crispian Balmer)