Ukrainian and Russian officials wrapped up a "productive" first day of new US-brokered talks in Abu Dhabi, Kyiv's lead negotiator said on Wednesday, as fighting in Europe's biggest conflict since World War Two raged on.

The two-day trilateral meetings come after Ukrainian President Volodymyr Zelensky said Russia had exploited a US-backed energy truce last week to stockpile munitions, attacking Ukraine with a record number of ballistic missiles on Tuesday.

"The work was substantive and productive, focused on concrete steps and practical solutions," Rustem Umerov, the head of Ukraine's National Security and Defence Council, wrote on X.

A US official, who offered comment on condition of anonymity, also called the talks productive and said they would continue on Thursday morning.

Zelenskiy, speaking in his nightly video address, said it was critical for the talks to lead to real peace and not offer Russia a new opportunity to continue the war. Ukraine's partners, he said, had to exert more pressure on Moscow.

"It must be felt now. People in Ukraine must feel that the situation is genuinely moving toward peace and the end of the war, not toward Russia using ‍everything to its advantage and continuing attacks," Zelensky said.

Zelensky also said Ukraine expected the talks to lead to a new prisoner exchange soon.

The president, interviewed by French television ⁠channel France 2, said the number of Ukrainian soldiers killed on the battlefield as a result of the war with Russia was estimated at 55,000.

Zelensky had previously cited a figure of more than 46,000 Ukrainian ‍servicemen killed in an interview with US television network NBC in February 2025. Shortly after the talks began, Russian forces struck a crowded market in eastern Ukraine with cluster munitions, killing at least seven people and wounding 15, the Donetsk region's Governor Vadym Filashkin said.

Photographs released earlier in the day by the United Arab Emirates' foreign ministry showed the three delegations sitting around a U-shaped table, with US officials seated at the centre, including special envoy Steve Witkoff and US President Donald Trump's son-in-law Jared Kushner.

Trump's administration has pushed both Kyiv and Moscow to find a compromise to end the ‍four-year-old war, but the two sides remain far apart on key points despite several rounds of talks with US officials.

"The good news is that for the first time in a very long time, we have technical military teams from both Ukraine and Russia meeting in a forum that we'll also be involved in with our experts," US Secretary of State Marco Rubio said in Washington on Wednesday. "I don't want to say talks alone is progress, but it's good that there's engagement going on."

The most sensitive issues are Moscow's demands that Kyiv give up land it still controls and the fate of the Zaporizhzhia nuclear power plant, Europe's largest, which sits in a Russian-occupied area.

Moscow ⁠wants Kyiv to pull its troops out of all the Donetsk region, including heavily fortified cities regarded as one of Ukraine's strongest defences, as a precondition for any deal.

Ukraine said the conflict should be frozen along current front lines and rejects any unilateral pullback of its forces.

Kremlin spokesperson Dmitry Peskov said on Wednesday that Russian troops would keep fighting until Kyiv made "decisions" that could bring the war to an end.

The first round of talks was held in the UAE last month. (Reuters)