Updated 10.3pm

US President Donald Trump called Ukrainian leader Volodymyr Zelensky a "dictator" Wednesday, widening a personal rift with major implications for efforts to end the conflict triggered by Russia's invasion three years ago.

The United States had provided funding and arms to Ukraine but, in an abrupt policy shift since coming to power, Trump has opened talks with Moscow.

"A Dictator without Elections, Zelenskyy better move fast or he is not going to have a Country left," Trump wrote on his Truth Social platform of the Ukrainian leader, whose five-year term expired last year.

Ukrainian law does not require elections during wartime.

On Tuesday Trump held a press conference in which he criticized Zelensky, repeated several Kremlin narratives about the conflict and called for an end to the war.

Zelensky in turn accused Trump of succumbing to Russian "disinformation," including Trump blaming of Kyiv for having "started" the war and echoing Kremlin questions over Zelensky's legitimacy.

"He refuses to have Elections, is very low in Ukrainian Polls, and the only thing he was good at was playing (Joe) Biden 'like a fiddle,'" said Trump in the Truth post of Zelensky.

"In the meantime, we are successfully negotiating an end to the War with Russia, something all admit only 'TRUMP,' and the Trump Administration, can do," Trump wrote in the post.

Zelensky was elected in 2019 for a five-year term, but has remained leader under martial law imposed following the Russian invasion.

His popularity has eroded, but the percentage of Ukrainians who trust him has never dipped below 50 percent since the conflict started, according to the Kyiv International Institute of Sociology (KIIS).

Starmer expresses support for 'democratically elected' Zelensky                  

British Prime Minister Keir Starmer assured Volodymyr Zelensky of his support, after US President Donald Trump had called the Ukrainian leader a dictator, his office said.

"The Prime Minister spoke to President Zelenskyy this evening and stressed the need for everyone to work together," said a Downing Street statement. Starmer "expressed his support for President Zelensky as Ukraine's democratically elected leader and said that it was perfectly reasonable to suspend elections during war time as the UK did during World War II."

"The Prime Minister reiterated his support for the US-led efforts to get a lasting peace in Ukraine that deterred Russia from any future aggression," it said. 

Trump calling Zelensky a dictator is 'wrong and dangerous': Scholz   

German Chancellor Olaf Scholz said that it was "wrong and dangerous" of US President Donald Trump to call Ukrainian leader Volodymyr Zelensky a "dictator".

"What is correct is that Volodymyr Zelensky is the elected head of state of Ukraine," Scholz told the Spiegel news site.

Earlier on Wednesday Trump called Zelensky "a dictator without elections".  legitimacy".

"The fact that proper elections can't be held in the middle of the war is reflected in the Ukrainian constitution and electoral law," he said.

Foreign Minister Annalena Baerbock also hit back at Trump's comments, branding them "absurd".

"If you look at the real world instead of just firing off a tweet, then you know who in Europe has to live in the conditions of a dictatorship: people in Russia, people in Belarus," Baerbock told broadcaster ZDF.

Earlier Berlin had also pushed back against Trump's claim that Kyiv had "started" the fighting.

"No one but Putin started or wanted this war in the heart of Europe," Baerbock said in a statement, adding that "we are working with all our might to further strengthen Ukraine".

She said "we are at an existential waypoint for security and peace in Europe" and that the goal was "achieving lasting peace for Ukraine -- safe and protected from future Russian aggression".

Baerbock said that any "false peace ... would only give Russia a respite for new military campaigns".

Regarding the fast-moving events since Trump spoke directly with Putin about ending the conflict, she said that "we must not allow ourselves to be confused" and "keep a cool head". 

Downplaying Europe's role on Ukraine "only plays into the hands" of Russia, she said. 

"I therefore advocate acting confidently towards the US administration."