Ukraine and Russia-backed separatists failed to reach an agreement on a prisoner exchange Wednesday after several hours of tense talks on the conflict in eastern Ukraine.

Representatives of Ukraine, Russia and the separatist rebel met in the Belarusian capital Minsk to discuss conditions for an “all for all” prisoner swap following a tentative agreement reached during Ukraine peace talks in Paris last week.

Ukrainian President Volodymyr Zelenskiy, who met with the leaders of Russia, France and Germany on Dec. 9, had hailed the prospective exchange as a key result of the Paris talks. He said he expected all 72 Ukrainian prisoners held by the separatists to return home before the year's end.

Natalia Nikonorova, a representative of Russia-backed rebels in Donetsk, speaks to the media as Vladislav Deinego, a representative of Russia-backed rebels in Luhanskleft, stands next, after peace talks for Ukraine, in Minsk, Belarus, Wednesday, Dec. 18, 2019. Ukraine and Russia-backed separatist rebels have failed to reach agreement on a prisoner exchange during another round of talks on the conflict in eastern Ukraine. (AP PhotoSergei Grits)

Natalia Nikonorova, a representative of Russia-backed rebels in Donetsk, speaks to the media as Vladislav Deinego, a representative of Russia-backed rebels in Luhanskleft, stands next, after peace talks for Ukraine, in Minsk, Belarus, Wednesday, Dec. 18, 2019. Ukraine and Russia-backed separatist rebels have failed to reach agreement on a prisoner exchange during another round of talks on the conflict in eastern Ukraine. (AP PhotoSergei Grits)

But Olga Kobtseva, a rebel representative in the so-called Contact Group in Minsk, said Wednesday's talks failed to produce an agreement. She cited Ukraine's refusal to absolve the rebels in its custody of criminal charges as the main stumbling block.

Another rebel envoy, Vladislav Dainego, said the parties also failed to agree on the areas where Ukrainian forces and the rebels would pull back from the front line to help maintain a lasting ceasefire.

There was no immediate comment from the Ukrainian side.

Natalia Nikonorova, a representative of Russia-backed rebels in Donetsk, speaks to the media after attending peace talks for Ukraine, in Minsk, Belarus, Wednesday, Dec. 18, 2019. Ukraine and Russia-backed separatist rebels have failed to reach agreement on a prisoner exchange during another round of talks on the conflict in eastern Ukraine. (AP PhotoSergei Grits)

Natalia Nikonorova, a representative of Russia-backed rebels in Donetsk, speaks to the media after attending peace talks for Ukraine, in Minsk, Belarus, Wednesday, Dec. 18, 2019. Ukraine and Russia-backed separatist rebels have failed to reach agreement on a prisoner exchange during another round of talks on the conflict in eastern Ukraine. (AP PhotoSergei Grits)

The fighting in eastern Ukraine that flared up in 2014 after Russia's annexation of Crimea has killed more than 14,000 and ravaged Ukraine's eastern industrial heartland.

A 2015 peace deal brokered by France and Germany helped reduce the scope of hostilities, but Ukrainian forces and the rebels have continued to exchange artillery salvos and gunfire.

During the talks in Paris, Zelenskiy, Russian President Vladimir Putin, French President Emmanuel Macron and German Chancellor Angela Merkel agreed to revive the peace process but made no progress on central issues — a timeline for holding local elections in eastern Ukraine and control of the borders in the rebel-held region.