Donald Trump will not fund Ukraine's fight against Russia's invasion if he is elected US president again, Hungarian PM Viktor Orban has said.

"He will not give a penny in the Ukraine-Russia war. That is why the war will end," the conservative premier said after meeting Trump in Florida, according to the BBC. 

The former US president has pledged to end the war "within 24 hours" if elected - but provided no details.

Orban is openly backing his long-term ally in the 2024 White House race.

"It is obvious that Ukraine cannot stand on its own feet," Orban told Hungary's M1 TV channel.

"If the Americans don't give money and weapons, along with the Europeans, then the war is over. And if the Americans don't give money, the Europeans alone are unable to finance this war. And then the war is over."

He added that Trump had "pretty detailed plans" on how to end the Russia-Ukraine war - but did not elaborate.