French Foreign Minister Laurent Fabius says talks on an international accord to combat climate change will be extended one day to help overcome some disputes.
Fabius said he would present a compromise text of an agreement on the morning of December 12 in hopes of securing a deal.
There are negotiators from some 195 countries at the United Nations Climate Change Conference, which was to end on December 11, the conclusion of two weeks of talks.
"The atmosphere is good, things are positive, things are going in the right direction," Fabius said.
But one source close to the negotiations told Reuters that "the night [into Friday] was very hard."
The overnight talks apparently showed continued disputes over issues such as how to balance actions by rich and poor countries to limit greenhouse gases and the long-term goals of an agreement to limit emissions.
Chinese President Xi Jinping and U.S. President Barack Obama spoke by telephone late on December 10 and pledged to continue cooperation on climate change, Chinese TV reported.