The leaders of Ukraine, Russia, France and Germany were due to hold peace talks on Wednesday aimed at halting a 10-month war in Ukraine where dozens were killed in the latest fighting.

China applauded the recent intensive mediation efforts in solving the Ukraine crisis, Foreign Ministry spokeswoman Hua Chunying said on Wednesday.

The summit was the climax of a frantic diplomatic push to prevent the worst East-West crisis since the end of the Cold War from escalating, with US President Barack Obama warning Russian President Vladimir Putin that Russia will be made to pay if the talks fail.

French President Francois Hollande and German Chancellor Angela Merkel, the driving forces behind the peace effort, will "try everything" to make it work, a French presidential source said, with "quite a lot of problems still to be resolved", just hours ahead of the summit expected to start early evening in Minsk.

Russian Foreign Minister Sergei Lavrov said on Wednesday there had been "noticeable progress" in preparations for a summit but suggested there were still questions about control over the border.

The bloodletting on both sides has been relentless in recent weeks as rebels have pushed a new offensive and Kiev forces have counterattacked.

At least 46 people were killed in the last 24 hours, including 16 in a devastating rocket attack on Kramatorsk, the Ukrainian government's eastern military headquarters and administrative hub.

In the rebel stronghold of Donetsk, city officials said that eight people had been killed on Wednesday. Rebels, who rarely announce military casualties, said they had lost seven fighters.

AFP-AP-Xinhua