While annual U.N. climate meetings almost always run into overtime, the abrupt announcement came as some officials and observers also said that wee-hours discussions had not run as smoothly as hoped. The talks had been due to end on Friday.
As at the outset two weeks ago, some nations remain at odds over issues such as how to balance actions by rich and poor to limit greenhouse gases, and also the long-term goals of any agreement to limit emissions that are warming the earth.
One source said the "night was very hard".
"Major countries have entrenched behind their red lines instead of advancing on compromise," said Matthieu Orphelin, spokesman for the Nicolas Hulot Foundation.
Fabius, speaking on French BFMTV, kept a positive tone.
"But the atmosphere is good, things are positive, things are going in the right direction," he said.
Separately, China`s President Xi Jinping and U.S. President Barack Obama spoke by telephone and said their countries would maintain cooperation on climate change, Chinese state television reported. It was unclear what they discussed, or whether the call signalled new divisions between the world`s largest emitters, who struck a landmark climate accord last year.
Xi said the two nations "must strengthen coordination with all parties and work together to ensure the Paris climate summit reaches an accord as scheduled", according to a report on state CCTV.
The latest draft pointed to a compromise on the once-formidable divide over how ambitious the deal should be in trying to control the rise in the earth`s surface temperature. It indicated apparent agreement on seeking a more ambitious goal to restrain the rise in temperatures to less than 2 degrees Celsius above pre-industrial levels.