US President Donald Trump has openly clashed with Ukraine’s President Volodymyr Zelensky in unbelievable scenes during a crucial meeting at the White House.

Simmering differences spilt into the open in front of the world’s stunned media on Saturday (AEDT) after the leaders met in the Oval Office.

Trump and Vance shouted at and berated Zelensky  — demanding gratitude, accusing him of being disrespectful and belittling Ukraine’s army and efforts in the war.

As tempers flared, Trump told Zelensky he either needed to “make a deal” or the United States was “out”.

Trump and Zelensky had been expected to sign a minerals deal for the US to recoup its investment in the Ukraine war.

However, Zelensky was seen swiftly departing the White House and a planned afternoon press conference was cancelled.

In one of the most heated moments, Trump and Vance shouted over Zelensky, with Vance pointing his finger at the Ukraine president.

“I think it’s disrespectful for you to come into the Oval Office and try to litigate this in front of the American media,” accused Vance.

“Offer some words of appreciation for The United States Of America and the president who is trying to save your country.”

Zelensky replied that he had said thank you many times, “including today”.

Trump interjected and raised his voice to join the pile-on.

“We’re trying to solve a problem. You’re right now, not in a very good position. You don’t have the cards right now.

“You’re gambling with World War Three. It’s going to be very hard to do business like this. You’ve got to be more thankful.”

Whenever Zelensky tried to speak or respond, Trump shouted over the top of him, repeating his own statements.

“You’re gambling with World War Three,” Trump said again.

“And what you’re doing is very disrespectful to…this country that’s backed you far more than a lot of people say they should have.”

Zelensky urged Trump to make “no compromises with a killer” and pointed out his softer approach towards Russian President Vladimir Putin.

At one point, Vance even asked Zelensky why he was not wearing a formal suit at the White House.

“Do you own a suit?” Vance asked, in reference to Zelensky’s black casual shirt with the Ukraine trident — a departure from his usual military fatigues.

Zelensky politely responded that he might wear a suit when the war was over.

International media covering the meeting said it was an unprecedented and historic moment between world leaders at the White House.

The fiery exchange lit up social media, with many commenting on Trump and Vance “bullying” Zelensky and engaging in “shameful” behaviour.

After Zelenky’s departure, Trump posted on Truth Social that Zelensky was not ready for peace.

“He disrespected the United States of America in its cherished Oval Office,” Trump said in a post.

“He can come back when he is ready for Peace.”

Zelensky posted his thanks to Trump and the US on X.

Zelensky, who gained billions of dollars’ worth of US weaponry and moral support from the previous administration under president Joe Biden for its fight against Russia, is facing a sharply different attitude from Trump.

Trump wants to quickly wind down the three-year war, improve ties with Russia and recoup money spent to support Ukraine.

Earlier, Trump welcomed Zelensky on his arrival at the White House before they headed for talks, lunch and then a joint press conference where they were to sign the agreement.

“I hope I’m going to be remembered as a peacemaker,” Trump said.

Trump told Zelensky that his soldiers have been unbelievably brave and that the United States wants to see an end to the fighting and the money put to “different kinds of use like rebuilding”.

The agreement negotiated in recent days would open Ukraine’s vast mineral wealth to the United States but does not include explicit US security guarantees for Ukraine, a disappointment for officials in Kyiv.

Trump says the presence of US businesses would serve as a form of guarantee.

How much the deal would be worth to the United States is not spelled out.

Trump has said he expects to gain hundreds of billions of dollars.

Zelensky has said he would not sign an agreement that would put his country in debt for generations.

Ukraine would contribute 50 per cent of “all revenues earned from the future monetisation of all relevant Ukrainian government-owned natural resource assets” to a reconstruction fund jointly owned and managed by the United States and Ukraine.

The agreement does not specify how the funds would be spent, or identify specific assets it covers, although it says they would include deposits of minerals, oil and natural gas as well as infrastructure such as gas terminals and ports.

-with AAP