Russia said it will hold security talks with the US and Ukraine in Abu Dhabi on Friday, but warned after a late-night meeting between President Vladimir Putin and three US envoys that a durable peace would not be possible unless territorial issues were resolved.

Kremlin aide Yuri Ushakov told reporters the talks, which began shortly before midnight and lasted some four hours, had been "substantive, constructive and very frank".

He said Russian Admiral Igor Kostyukov would head Moscow's team at the three-way security talks, and investment envoy Kirill Dmitriev would meet separately on economic issues with Steve Witkoff, the envoy of President Donald Trump.

But while outlining the next steps, Ushakov stopped short of hailing any major breakthrough.

"Most importantly, during these talks between our president and the Americans, it was reiterated that without resolving the territorial issue according to the formula agreed upon in Anchorage, there is no hope of achieving a long-term settlement," he said, referring to last year's Trump-Putin summit in Alaska.

Ushakov said Putin underlined that Russia was "sincerely interested" in a diplomatic solution.

He added, however: "Until this is achieved, Russia will continue to consistently pursue the objectives of the special military operation. This is especially true on the battlefield, where the Russian armed forces hold the strategic initiative."

Ukraine is enduring its harshest winter of the war as Russia mounts heavy missile and drone strikes on its energy infrastructure. With temperatures way below freezing, hundreds of thousands of people in Kyiv and other cities have suffered long power cuts and been left without heating.

Ukraine cites this as evidence that Putin has no real interest in peace, which Moscow disputes. It says Russia's gradual advances have come at enormous cost.

New US participant in talks

Putin, Ushakov and Dmitriev took part in the talks on the Russian side.

On the US side, Witkoff and Trump's son-in-law Jared Kushner, who last met Putin in the Kremlin in early December, were accompanied by Josh Gruenbaum, newly appointed by Trump as a senior adviser to his Board of Peace, which will seek to tackle world conflicts.

The talks were the latest stage in a drive by Trump to bring an end to the deadliest conflict in Europe since World War Two, now approaching the end of its fourth year.

Trump said on Wednesday that Putin and Ukrainian President Volodymyr Zelenskiy would be "stupid" if they failed to come together and get a deal done.

Witkoff was upbeat before the Moscow talks, saying many months of negotiations had come down to a single issue.

He did not specify what that was, but the question of territory singled out by Ushakov would not come as a surprise to many.

A key stumbling block is Putin's demand that Ukraine surrender the 20% it still holds of the eastern region of Donetsk. Zelenskiy has refused to give up land that Ukraine has successfully defended at great cost through years of grinding, attritional warfare.

Russia also demands that Ukraine renounce its ambition to join NATO, and rejects any presence of NATO troops on Ukrainian soil following a peace deal.

Zelenskiy, after meeting Trump in Switzerland on Thursday, said the terms of security guarantees for Ukraine had been finalised, but that the issue of territory remained unsolved.

Ushakov praised the Americans for setting up Friday's security meeting with Russia and Ukraine in Abu Dhabi.

"The Americans, it must be acknowledged, have done a great deal to prepare for it, and they hope that this meeting will be successful and will open up prospects for progress on the entire range of issues related to ending the conflict and reaching a peace agreement," he said.