Donald Trump's special envoy was in Kyiv on Wednesday, saying he was there to "listen" to Kyiv's concerns, a day after the US president tore into his Ukrainian counterpart in a surprise press conference.

Speaking on Tuesday, after Russian and US officials met in Saudi Arabia for their first high-level talks in over three years without Ukraine taking part, Trump appeared to blame Ukrainian President Volodymyr Zelensky for having "started" the war.

"Today I heard, 'oh, well, we weren't invited.' Well, you've been there for three years... You should have never started it. You could have made a deal," Trump told reporters at his Mar-a-Lago resort in Florida.

Zelensky had chided the US-Russia talks for not including Kyiv, saying efforts to end the war must be "fair and involve European countries."

Trump's special envoy for Ukraine, Keith Kellogg, arrived in Kyiv by train on Wednesday morning on what he said was a mission to "sit and listen" to Kyiv's concerns.

"We understand the need for security guarantees... Part of my mission is to sit and listen and say: what are your concerns?" Kellogg said in a video posted by Ukraine's Suspilne news outlet.

Russia and the United States agreed on Tuesday to establish teams to negotiate a path to ending the war.

Kyiv and its European allies have become alarmed at being cut out of the process with Russia to end the conflict. (AFP)