Foreign ministers from Russia, Ukraine, Germany, and France have started talks in Paris on ways to halt the 15-month war in eastern Ukraine.
Fighting between Ukrainian government forces and pro-Russian separatists has killed more than 6,400 people in Ukraine's Donetsk and Luhansk regions since April 2014.
A German- and French-brokered cease-fire deal signed in Minsk in February has proven extremely shaky, with sporadic clashes continuing in parts of the conflict zone.
Ahead of the closed-door meeting on June 23, German Foreign Minister Frank-Walter Steinmeier said recent deaths show that "the cease-fire isn't just fragile but that the daily violations are becoming more frequent."
"Without a cease-fire, all the other factors won't come together," he warned.
