VIENNA: France and Germany's foreign ministers left Iranian nuclear talks in Vienna on Sunday saying that a deal remains uncertain, but US Secretary of State John Kerry remained in the Austrian capital for further negotiations.
"I cannot say with certainty whether we will get a deal" by a July 20 deadline, German Foreign Minister Frank-Walter Steinmeier told reporters.
"It is now up to Iran to decide whether to take the path of cooperation with the international community. ... I hope that the days left until July 20 will be enough to create some reflection in Tehran," he said.
"The ball is Iran's court."
French Foreign Minister Laurent Fabius for his part said that talks between Iran and the five permanent members of the UN Security Council plus Germany would continue.
"We had a deep discussions but we have still not reached a deal," Fabius told reporters before leaving Vienna, describing the negotiations as "useful".
Kerry was still in Vienna, however, and was due to hold talks later Sunday with Iranian Foreign Minister Mohammad Javad Zarif.
The talks are aimed at securing a historic deal that would kill off once and for all worries that Iran -- which denies any such aim -- might develop nuclear weapons under the guise of its civilian programme.
The six powers want Iran to reduce dramatically the scope of its nuclear programmes for a lengthy period of time and submit to tougher inspections from the UN atomic watchdog.
The Islamic republic in return wants a lifting of all UN and Western sanctions that have crippled its economy, in particular its vital oil sector.
The July 20 deadline can in theory be extended but only if both sides agree and the United States in particular is opposed to such a move unless Tehran offers major concessions first.