Ukraine's representative, former president Leonid Kuchma, left the talks in Minsk, Belarus, telling Interfax news agency that separatist officials had undermined the meeting by making ultimatums and refusing "to discuss a plan of measures for a quick ceasefire and a pull-back of heavy weapons".
Denis Pushilin, one of the separatist officials, told the Russian news agency RIA that they were ready for dialogue "but not ready for ultimatums from Kiev while shelling by their forces is going on in the background of towns in the Donbass (industrialised eastern Ukraine)".
The meeting of the "contact group", which also involves a Russian envoy and an official from the Organization for Security and Cooperation in Europe, took place in the Belarussian capital even as fighting between Kiev's forces and the Russian-backed rebels raged on in Ukraine's east, claiming more civilian and military lives, Reuters reported.
The outcome dashed hopes that a new ceasefire could be put together soon to stem nine months of conflict pitting Ukrainian government forces against Russian-backed separatists who have declared "people's republics" in eastern Ukraine.
Shortly before the Minsk talks broke up, German Chancellor Angela Merkel, French President Francois Hollande and Russia's Vladimir Putin in a three-way phone call had expressed the hope the meeting would at least produce a ceasefire agreement.
More than 5,000 people have died since the conflict erupted last April following Russia's annexation of Crimea in response to the ousting of a Moscow-backed president in Kiev by street protests.