KIEV: Kiev’s pro-Western leaders and mediators hoped to reach a “binding” truce with pro-Russian separatists Saturday despite Ukraine suffering one of its bloodiest days yet in the nine-month conflict with 15 troops killed.

“In the last day, 15 soldiers died and 30 more were wounded. That is the figure for the whole frontline,” Defense Minister Stepan Poltorak said.

The death toll is the highest one-day loss for Ukraine’s military since the signing in September of a nominal cease-fire deal that has collapsed totally in recent weeks.

Representatives from both sides, as well as mediators from the Organization for Security and Cooperation in Europe, were to meet in the Belarussian capital Minsk on Saturday for urgent Kremlin-backed talks to agree a new truce.

With the civilian death toll also mounting in rebel regions Donetsk and Lugansk, the truce in addition should provide for the “unrestricted supply of basic goods and humanitarian assistance,” the OSCE said.

Separatist negotiators flew into Minsk on Saturday, as did Kiev’s envoy, former President Leonid Kuchma, for the latest talks aimed at defusing fighting that has left at least 5,100 people dead.

Ukraine has insisted on the presence of Donetsk insurgency commander Alexander Zakharchenko and leader of the separatist Lugansk region Igor Plotnitsky at the talks, rather than their representatives.

The insurgents last week pulled out of peace talks and announced the start of an offensive designed to expand their control over a much broader swathe of the industrial southeast.

They said Friday they would push their offensive “until the entire Donetsk and Lugansk regions are freed” of Ukrainian troops should the talks fail.

At least 24 people were killed in fighting on Friday, with Grad rocket attacks on the separatists’ self-proclaimed capital Donetsk continuing late into the night, an AFP correspondent said.

Fighting is raging around the strategic Ukrainian-controlled transport hub of Debaltseve, some 50 kilometers northeast of the rebel stronghold of Donetsk.

The town of 25,000 people was built around a railroad connecting the two rebel centers of the Russian-speaking southeast.

Defense Minister Poltorak for the first time said that separatist forces had taken “partial” control of Debaltseve, where rebels claim to have surrounded some 8,000 Ukrainian troops.