The US-mediated peace talks in Switzerland have been taking place as US President Donald Trump has twice in recent days suggested it was up to Ukraine and Zelenskiy to take steps to ensure the talks were successful.
"Yesterday's meetings were indeed difficult, and we can state that Russia is trying to drag out negotiations that could already have reached the final stage," Zelenskiy wrote on X on Wednesday, following media reports that the first day of talks had been tense.
Minutes after Zelenskiy's comments, Russia's state news agency RIA reported that the talks had ended. Russian chief negotiator Vladimir Medinsky told reporters in the lobby of the hotel where talks took place in Geneva that further negotiations would be held soon, without specifying a date.
A Ukrainian official confirmed the talks in Geneva had ended, saying they had lasted about two hours.
In an interview with US website Axios published on Tuesday, Zelenskiy was quoted as saying it was "not fair" that Trump kept publicly calling on Ukraine, not Russia, to make concessions in negotiating terms for a peace plan.
Zelenskiy also said any plan requiring Ukraine to give up territory that Russia had not captured in the eastern Donbas region would be rejected by Ukrainians if put to a referendum.
"I hope it is just his tactics and not the decision," Axios quoted Zelenskiy as saying in the interview.
Trump had told reporters on Monday that "Ukraine better come to the table fast. That's all I'm telling you."
The talks came just days before the fourth anniversary of Russia's 2022 invasion of its much smaller neighbour.
Hundreds of thousands of people have been killed, millions have fled their homes, and many Ukrainian cities, towns and villages have been devastated by the conflict.
Russia denies deliberately targeting civilians. The head of the Ukrainian delegation, Rustem Umerov, said Tuesday's talks had focused on "practical issues and the mechanics of possible decisions", without providing details.
However, Russian news agencies quoted a source as saying that the Tuesday talks were "very tense" and lasted six hours in different bilateral and trilateral formats.
Before the talks began, Umerov had played down hopes for a significant step forward in Geneva, saying the Ukrainian delegation was working "without excessive expectations".
The Geneva meeting follows two rounds of US-brokered talks in Abu Dhabi that concluded without a major breakthrough as the two sides remained far apart on key issues such as the control of territory in eastern Ukraine.
Russia occupies about 20 per cent of Ukraine's national territory, including Crimea and parts of the eastern Donbas region seized before the 2022 full-scale invasion.
Its recent air strikes on energy infrastructure have left hundreds of thousands of Ukrainians without heating and power during a harsh winter.