Leaders of France, Germany, Ukraine and Russia will hold a new telephone call late on Wednesday on the Ukrainecrisis, French government spokesman Stephane Le Foll said.

"The leaders want to push ahead with support and implementation of this accord," Le Foll told a regular news briefing of a ceasefire agreement supposed to have taken effect this weekend but which failed to stop an assault by Russian-backed separatists on the strategic eastern town of Debaltseve.