Ukraine's President Volodymyr Zelensky said he was "happy" with US mediators' change in approach during talks with Russia in Abu Dhabi, set to continue into a second day on Wednesday, but emphasised the need for security guarantees for his country.

Representatives from Kyiv and Moscow began negotiations in the Emirati capital on Tuesday, the first since February when discussions reached a stalemate and Washington was sidetracked by the Iran war.

US envoys, including President Donald Trump's son-in-law Jared Kushner and businessman Steve Witkoff, are mediating the talks.

The first meeting lasted several hours and aimed to make progress towards resolving the war in Ukraine and -- according to Washington -- working on a "new" security framework that includes Europe.

A source on Russia's delegation said further talks on Wednesday would start at 12 noon in Abu Dhabi (0800 GMT).

Kushner told delegates the United States had "narrowed the gaps" between the warring sides, without providing details, and hoped to move towards a "solution" to Europe's worst conflict since World War II.

Zelensky, speaking in Copenhagen on Tuesday, said the talks were "constructive and quite substantive", adding his team had reported that humanitarian issues and security guarantees were among the topics discussed.

Asked about changes in the approach to peace talks by Kushner and Witkoff, Zelensky said: "I see changes. I'm very happy with what I hear."

The Ukrainian president said negotiators in Abu Dhabi were working on a "large-scale exchange of prisoners", adding that US officials would travel to Russia to discuss the matter further.

However, fighting continued overnight. The governor of Russia's Leningrad region, Aleksandr Drozdenko, posted on Telegram that a Ukrainian drone barrage had sparked a fire at Ust-Luga, a key Baltic port for oil exports.

The attack wounded three workers, he said in a later post on Wednesday, adding that Russian air defences had downed 150 drones in the region during the night.

In Paris, US Secretary of State Marco Rubio hailed this week's discussions as "very productive" and called for Europeans to be eventually included at the negotiating table "because they are part of solving this problem".

Europe has been rattled as Trump floated a deal with Russia on rewriting European post-war security, also worrying that Washington will force Kyiv to accept a de-facto defeat.

Kushner said the United States hoped to "create a new framework" of security between Ukraine, Russia and Europe that will secure "decades, if not centuries, of peace".

Moscow, which several weeks before invading Ukraine issued an ultimatum to Western countries to roll back troops from eastern Europe, had also said this was a priority.

Ukraine has warned against a "Yalta 2.0", referring to Western leaders dividing Europe with the Soviet Union after World War II, and the EU has said security arrangements can only be discussed after a ceasefire.

"Putin wants the USSR back," Zelensky told Danish media.

Putin has repeatedly turned down broader ceasefire offers and vowed his troops will press on in Ukraine.

In a sign it is serious about reviving its demand to review Europe's decades-old security arrangement, Russia included a diplomat, Sergei Ryabkov, who lodged Moscow's pre-invasion demand for NATO to pull back from eastern Europe.

A Russian delegation source had said that settling the war was "merely one item on the agenda", and that Moscow's main objective was reviewing security "for the entire continent".

Kyiv's chief negotiator Rustem Umerov met the US envoys and European, EU and NATO officials before the negotiations.

The top US and NATO general in Europe, Alexus Grynkewich, is also taking part.

In a joint statement, the Europeans, Ukraine, the United States and NATO reaffirmed their "shared commitment to a strong post-war European security architecture".

Umerov said Kyiv's priorities remained securing a ceasefire and security guarantees. "Our people are waiting to end this war," he said.

Ukrainian and French foreign ministers in Paris commended US efforts to push for "partial truces", which could serve as a "first step toward a complete and unconditional ceasefire".

Last month, a local truce in Ukraine's Kherson region brokered by US First Lady Melania Trump became the longest pause in fighting during the war.

Kyiv is also pushing post-war support for its army.

A senior Ukrainian source told AFP Ukraine wanted at least 10 years of financial support to sustain an 800,000-strong army able to defend any future Russian attack.

Trump hinted before the talks that Kyiv might have to give up land, saying: "They're going to end up with a little bit different shape."

Russia's troops have ground westwards but have not been able to seize the whole of the coveted Donetsk region, and Moscow demands Kyiv surrender the parts of the embattled area it controls.

Russia continues to pound Ukraine and its energy network, raising fears of another winter without heating, running water or electricity for millions of Ukrainians.

@AFP