US President Donald Trump said on Wednesday (Aug 13) he would seek a three-way meeting with Volodymyr Zelenskyy and Vladimir Putin immediately after his Alaska summit with the Russian leader aimed at ending the three-year war in Ukraine.

Trump spoke after what he described as a "very good" call with European leaders, including Zelenskyy - even as Russian forces made their biggest advance into the Ukrainian president's country in more than a year.

"If the first one goes okay, we'll have a quick second one," Trump told reporters as he was questioned about the face-to-face in the Alaskan city of Anchorage with his Russian counterpart, set for Friday.

"I would like to do it almost immediately, and we'll have a quick second meeting between President Putin and President Zelenskyy and myself, if they'd like to have me there."

The high-stakes summit comes with Trump struggling to broker an end to the conflict, and Zelenskyy and his European allies earlier urged the Republican to push for a ceasefire.

The stepped-up Russian offensive, and the fact Zelenskyy has not been invited to Anchorage, have heightened fears that Trump and Putin could strike a deal that forces painful concessions from Ukraine.

The US leader promised dozens of times during his 2024 election campaign to end the conflict on his first day in office but has made scant progress towards securing a peace deal.

He threatened "secondary sanctions" on Russia's trading partners over its invasion of Ukraine but his deadline for action came and went last week with no measures announced.