Volodymyr Zelensky warned he would reject any peace negotiated between the United States and Russia as European leaders rounded on Donald Trump.
The Ukrainian president insisted European Union leaders must be given a seat in any negotiations to end the war.
“It’s important that everything does not go according to Putin’s plans, in which he wants to do everything to make his negotiations bilateral [with the US],” Mr Zelensky told reporters before travelling to the Munich Security Conference in Germany.
“We, as an independent country, simply will not be able to accept any agreements without us,” he added.
The Kremlin said it believed its main interlocutor in the talks would be Washington, even after Ukraine had joined the talks “one way or another”.
Dmitry Peskov, its spokesman, told state television that Moscow would “expand working contacts in the coming days and weeks” with the US.
Mr Zelensky described Mr Trump’s decision to speak to Putin first about the talks as “unpleasant”.