US Vice-President JD Vance's cousin has criticised him and President Donald Trump for "belittling" Volodymyr Zelensky during the three men's Oval Office showdown in February.

"There's a certain level of decorum that I expect from political leaders, especially in front of cameras," Nate Vance - who spent three years volunteering with the Ukrainian military after Russia's full-scale invasion - told the BBC.

It follows his earlier comment that Trump and Vance were acting like "useful idiots" for President Vladimir Putin in their handling of the conflict.

Last month US and Russian officials held direct talks on ending the war. US and Ukrainian officials are currently in Saudi Arabia for talks.

Nate Vance told the BBC's PM programme on Monday that he was "not happy" with the way in which the White House meeting had been handled by his cousin and Trump.

"I'm kind of attached to the Ukrainian issue but, looking at that, if it were some other completely neutral issue and I saw White House officials and hack journalists that are political belittling a foreign leader, I'd be like 'what the hell is going on?'" he told the BBC.

The televised Oval Office meeting between the leaders quickly turned heated, with Trump threatening to withdraw support from Ukraine if a deal was not made and accusing the Ukrainian President of "gambling with World War Three".

Vance called Zelensky "disrespectful" for "litigating" the dispute in front of the media and accused him of not expressing gratitude for America's support during the war.

Nate Vance said that he did not agree that Zelensky had failed to show appreciation. "Zelensky does a daily or nightly address and thanks everyone who supports Ukraine on a daily basis," he said.

He said that perhaps the Ukrainian leader had not shown "enough deference to Donald Trump" but that it would be "odd for my cousin and Donald Trump to ask for deference because they've been actively working against his initiatives for the past three years".

Zelensky was eventually asked to leave the White House and a planned news conference was cancelled.

Following the meeting, the Trump administration halted military aid, satellite imagery and intelligence sharing to Kyiv.