Diplomats grappled to secure a landmark deal at talks on Iran's nuclear programme today, but Tehran raised the prospect of negotiations being put off after cracks emerged among world powers.
France in particular voiced concerns about a proposed deal, questioning whether it would go far enough to limit Tehran's nuclear ambitions.
As intensive negotiations continued in Geneva, Iranian President Hassan Rouhani urged world powers not to miss the chance for a deal.
"I hope that the P5+1 group make the most out of this exceptional opportunity that the Iranian nation has offered to the international community, so that we can reach a positive result within a reasonable timeframe," he was quoted as saying by the official IRNA news agency.
The US, British, French, German and Russian foreign ministers had rushed to Geneva to join the talks amid hopes of a breakthrough toward ending the decade-old standoff on Iran's nuclear efforts.
US Secretary of State John Kerry cut off a Middle East tour to fly to Geneva and, despite reports the talks had broken down, joined Iran's foreign minister and the chief EU diplomat, Catherine Ashton, for fresh negotiations this evening.
The proposed agreement -- seen as a first step ahead of further talks on a final deal -- would see Iran freeze parts of its nuclear programme for as long as six months in exchange for some relief from the sanctions battering its economy.
Officials have repeatedly said progress is being made but cautioned that serious obstacles remain.
After several meetings with fellow diplomats, Iranian Foreign Minister Mohammad Javad Zarif said there were still "disagreements" on some questions and pointed to divisions among world powers.
"There are differences of opinion within the P5+1 group," he was quoted as saying by Iranian news agency ISNA, adding that negotiations would not continue into Sunday if a deal was not reached.
"If we do not reach an agreement tonight, the talks will be resumed in the next seven or 10 days," he said.
Saying there was "no certainty" of a deal, French Foreign Minister Laurent Fabius said Paris did not accept an initial draft of the deal as presented.
The French foreign minister cited calls for Iran to halt operations at its Arak nuclear reactor and questions about enriched uranium stockpiles as particular points of contention.
