The call was initiated by Zelenskiy, and followed a five-hour meeting that Witkoff and Kushner had with Russian President Vladimir Putin in Moscow on Tuesday, reports Axios, citing sources.

A well-informed source told Axios that Witkoff and Kushner gathered information from both sides and pressured both Putin and Zelensky to make the concessions needed to reach a deal.

"Talking about territories was difficult," the source said. He noted that Russia still requires Ukraine to withdraw from the parts of Donbass it controls.

Another key issue was US security guarantees to Ukraine. One source said the parties had made significant progress and were closer to an agreement but that more work was needed to ensure both sides had similar interpretations of the draft security guarantee.

"The main challenging issues concern territorial issues and security guarantees. Our goal is to ensure that the agreed solutions are realistic, fair and sustainable," Ukrainian Ambassador to Washington Olga Stefanishyna told Axios today.

Today, Zelensky held a two-hour conversation with Trump's advisers Steve Witkoff and Jared Kushner, and he described the talks as"very focused" and "constructive".

Umerov and Gnatov are expected to return from Miami to Europe and brief Zelensky on the US proposals in London on Monday.

Further talks and meetings with Witkoff and Kushner are expected later in the week.

"Negotiations will continue, and face-to-face meetings are key," said Ukrainian ambassador Stefanishina.