US President Donald Trump said on Saturday he would speak by phone with Russian President Vladimir Putin to end the "bloodbath" in Ukraine, a day after the first direct talks between Russia and Ukraine in more than three years.

Trump, who has been pressing Russia to agree a 30-day unconditional ceasefire, said he would speak with him by phone on Monday. Kremlin spokesman Dmitri Peskov told the state TASS news agency the call was "being prepared."

Earlier on Saturday, the Kremlin had said that a meeting between Putin and Ukrainian President Volodymyr Zelensky would be possible only after both sides reach an agreement.

That came a day after direct talks between the two countries led only to an agreement for another exchange of prisoners.

Early on Saturday, a Russian drone attack on a minibus carrying evacuated civilians in Ukraine's eastern Sumy region killed nine people and wounded five, local authorities said.

Zelensky, denouncing the attack and Russia's refusal so far to agree a ceasefire, repeated his call for fresh sanctions against Moscow.

"Without stronger sanctions, without stronger pressure on Russia, there will be no real diplomacy there," he insisted.

On Friday in Istanbul, the first direct Ukraine-Russia talks since the spring of 2022 – shortly after Moscow's full-scale operation in Ukraine began that February – led to an agreement to exchange 1,000 prisoners each.

Ukraine's top negotiator, Defence Minister Rustem Umerov, said the "next step" would be a meeting between Zelensky and Putin.

Russia said it had taken note of the request. (AFP)