Work towards an agreement to temporarily halt Iran's nuclear program in exchange for the easing of sanctions failed on Saturday as France took issue with the proposed deal's ability to sufficiently curb the nation's nuclear capacities.
"A lot of concrete progress has been achieved but some differences remain," European Union High Representative Catherine Ashton and Iranian Foreign Minister Mohammad Javad Zarif said in a joint statement following the meeting.
According to the Associated Press, the French hoped to secure tougher conditions than those agreed to by the other nations engaged in talks, including the U.S.
In particular, "Iran's refusal to suspend work on a plutonium-producing reactor and downgrade its stockpile of higher-enriched uranium" were at issue for the French.
The new development raised doubts about the likelihood that the marathon talks, now in their third day, would produce a once-in-a-decade deal on Iran's nuclear program by Sunday.
Secretary of State John Kerry flew to Geneva on Friday, in the middle of a planned trip to the Middle East, initially prompting optimism for the outcome of the talks.
This story was updated at 8:30 p.m.