Speaking to reporters in Washington, DC, on Monday, Trump argued that Ukraine could have secured a better agreement if Zelensky had followed his advice earlier in the conflict.

The remarks came after a reporter questioned Trump about Zelensky's criticism of his position on the war.

"Zelensky says you're on the wrong side of history on this one," a reporter put to him.

"Zelensky says? Zelensky doesn't know what he's talking about. Zelensky is a man that should have had this war settled a long time ago. If he would have listened to me, he would have made a much better deal a long time ago and had half a million people living from his side. And to be honest, I don't think I think it's time for somebody else to negotiate on behalf of Ukraine, because what's happened, very little land is moved, but a million people, a tremendous number of people are dead," Trump hit back.

Trump continued his criticism, arguing that Ukraine had suffered significant losses and that a different negotiator might be needed.

"They're losing their male population . Ukraine could have had this thing settled a long time ago if he would have listened to me. And you remember the Oval Office; he would have had this settled a long time ago. Maybe it's time for Zelensky to get somebody else to negotiate," he reiterated.

The comments followed a series of disagreements between Washington and Kyiv over peace negotiations, Ukrainian attacks on Russian oil facilities and US cooperation with Moscow.

On Sunday, Trump wrote on social media that he was "in the process of negotiating Peace in the war between Russia and Ukraine" and that "great progress is being made".

However, he also criticised Ukraine's attacks on Russian diesel refineries, claiming that "Zelensky is using Diesel Refineries in Russia as a target, knowing that these attacks are seriously hurting the world diesel markets".

Trump added that "Russia is, nevertheless, sending, at a low price, millions of barrels of diesel to the World."

He further accused Zelensky of being unwilling to end the conflict despite financial assistance from Europe and the previous US administration.

"Zelensky doesn’t care, and frankly, with all of the money that Europe is famously giving him, and that Crooked Joe Biden gave him in the past, he doesn’t want to end this war, and probably never did. He could have made a better deal two years ago than he can now. His country is in shambles, a large portion of his land is lost, his oceans and seas are gone, and his male population is low, wounded, and/or dead," Trump said.

The dispute intensified after Trump described Zelensky on Thursday as 'not a good guy for us to deal with… he doesn't want to settle'.

The US president called for elections in Ukraine, criticised attacks on Russian refineries as 'a disgrace' and claimed that Zelensky was 'more difficult to deal with than Putin'.

Zelensky had earlier told a UK media outlet that Ukraine would resume attacks on Russian refineries after restricting them for three days.

"The block [on attacking refineries] is out. We’re done."

On Wednesday, Zelensky also accused Trump of 'betraying' him following suggestions that Washington had suspended intelligence sharing with Ukraine. Trump denied the allegation.

The US president subsequently called for a 'new Ukrainian president' after Zelensky criticised Washington's latest diesel agreement with Russia.

Tensions have also emerged between Kyiv and Elon Musk over satellite internet services.

Zelensky accused Musk's SpaceX of cutting Starshield satellite internet access and warned that 'people will die'.

Musk responded on social media that it was "time for Zelensky to go".

On Friday, Zelensky joined European Union leaders amid reports of concern over his worsening relationship with Washington.

He also announced plans to accelerate production of interceptor drones , saying prototypes already existed but needed to be deployed effectively and produced at greater scale.

Zelensky said combat aircraft were currently carrying much of the burden of intercepting jet-powered drones.

Earlier on Thursday, he chaired a meeting of Ukraine's Supreme Commander-in-Chief's Staff focused on increasing production of high-speed drone interceptors and involving businesses in manufacturing air defence systems.

Zelensky also said Kiev was preparing for talks with envoys of the US president , who were expected to hold meetings in both Ukraine and Russia.

Speaking about the prospects of ending the conflict , Putin said legal issues surrounding Ukraine's leadership would need to be clarified if both sides reach a settlement.

Under Ukraine's constitution, the president is limited to two five-year terms. Putin argued that questions remain about how President Zelensky's extended time in office should be interpreted.

"Under the Ukrainian Constitution, the president is limited to two five-year terms. If we agree with those who believe that President Zelensky extended his term legally, then two years have already passed. So is he now going to run for another five years? That is not permitted under the Constitution."

Putin continued: "Only two five-year terms, or ten years in total. But what about the two years he has already spent in power? There are many questions."

Despite raising concerns over the legal framework, Putin said Russia remains willing to pursue a negotiated end to the conflict.

"But if we do eventually get to signing the documents, I think that if there is a desire to end the armed conflict peacefully - and Russia does have such a desire - we will find those who need to sign the relevant document."

He added that the legal aspects of any agreement would require further examination by specialists.

"It's a very important matter, but it is, after all, a legal issue."

Putin said that if the conflict ultimately comes to an end, both sides should be able to recognise that outcome.

"With regard to what we might say to one another when the conflict comes to an end, the very least we could and should say is, 'Thank God it's all over.'"

"But the legal side to the matter must, naturally, be looked into at the specialists level. I think this is understandable."