US and Russian officials opened talks in Saudi Arabia on Monday on a partial ceasefire in the Ukraine war, a day after delegates from Washington and Kyiv had their own discussions.

US President Donald Trump is pushing for a rapid end to the three-year war and hopes talks in Riyadh could pave the way for a breakthrough.

Both sides have proposed different plans for temporary ceasefires, but cross-border attacks have meanwhile continued unabated.

Originally planned to take place simultaneously to enable shuttle diplomacy – with the United States going back and forth between the delegations – the talks are now taking place one after the other.

The meeting between the Ukrainian team, led by defence minister Rustem Umerov, and the Americans finished up late on Sunday night.

"The discussion was productive and focused – we addressed key points including energy," Umerov said on social media, adding Ukraine was working to make its goal of a "just and lasting peace" a reality.

Trump envoy Steve Witkoff voiced optimism that any agreement struck would pave the way for a "full-on" ceasefire.

"I think you're going to see in Saudi Arabia on Monday some real progress, particularly as it affects a Black Sea ceasefire on ships between both countries. And from that you'll naturally gravitate to a full-on shooting ceasefire," he told Fox News.

But the Kremlin on Sunday downplayed expectations of a rapid resolution.

"We are only at the beginning of this path," Kremlin spokesman Dmitry Peskov told Russian state TV.

He said there were many outstanding questions over how a potential ceasefire might be implemented.

Russian President Vladimir Putin has rejected a joint US-Ukrainian call for a full and immediate 30-day pause, proposing instead a halt in attacks only on energy facilities. (AFP)