Talks in Istanbul between Turkey's top diplomat and a Russian delegation have ended with the two sides set to meet again with the Ukrainians, a foreign ministry source said.
The meeting between Foreign Minister Hakan Fidan and the delegation headed by Vladimir Medinsky at Istanbul's Dolmabahce Palace finished late, the source added.
"The meeting has ended. Tomorrow there will be more talks in different formats," he said, indicating that "trilateral talks between Russia, Ukraine and Turkey are on the agenda".
There would also be a round of US, Ukrainian and Turkish talks.
"It has not been finalised whether there will be a quadrilateral format," grouping officials from all four countries, he added.
Russia and Ukraine had been expected to meet in Istanbul for their first direct peace talks in more than three years.
But as the day wore on without any concrete indications of timings, it remained unclear when the sides would meet, with US Secretary of State Marco Rubio suggesting the meetings would happen tomorrow.
Hopes of a major breakthrough were further dented by US President Donald Trump who said there would be no movement without a meeting between himself and Russian President Vladimir Putin.
(Watch: Donald Trump says nothing will happen on Ukraine talks until he and Vladimir Putin meet)
Speaking to reporters on the sidelines of a NATO summit in the southern coastal city of Antalya, Mr Rubio said he would meet Ukraine's top diplomat, Andriy Sybiga in Istanbul.
And he said a lower-level US official would meet with the Russian delegation.
"I want to be frank... we don't have high expectations of what will happen tomorrow," Mr Rubio told reporters, saying he hoped Turkey would work to bring the two delegations together.
Ukrainian President Volodymyr Zelensky, who had flown to Turkey in the hope of meeting a top-level Russian delegation in Istanbul, instead stayed in Ankara where he held talks with Turkey's Recep Tayyip Erdogan.
With Russia showing up with a relatively low-level team, Mr Zelensky then decided to send his defence minister, Rustem Umerov, to lead the Ukrainian delegation.
Mr Medinsky, who heads the Russian team, is a hawkish adviser to Russian President Vladimir Putin who has questioned Ukraine's right to exist and led failed talks in 2022 at the start of the war.
Diplomatic confusion
The diplomatic disarray was symptomatic of the deep hostility between the warring sides and the unpredictability injected by Mr Trump, whose interventions since returning to the White House in January have often provoked dismay from Ukraine and its European allies.
While Mr Zelensky waited in vain for Mr Putin in Ankara, the Russian negotiating team sat in Istanbul with no one to talk to on the Ukrainian side.
Some 200 reporters milled around near the Dolmabahçe Palace on the Bosphorus strait that the Russian side had specified as the venue for the talks.
The enemies have been wrestling for months over the logistics of ceasefires and peace talks while trying to show Mr Trump they are serious about trying to end what he calls "this stupid war".
Hundreds of thousands have been killed and wounded on both sides in the deadliest conflict in Europe since World War II.
The US has threatened repeatedly to abandon its mediation efforts unless there is clear progress.
Read more:
Ukraine-Russia peace talks in Turkey: What we know
Ukraine peace talks: What are Kyiv and Moscow's positions?
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