Following the row in the Oval Office, several leading Republicans backed how the meeting had been handled by Trump and criticised Zelensky, according to BBC.

Senator Lindsey Graham - once a staunch supporter of Ukraine - told reporters that Zelensky "either needs to resign and send somebody over that we can do business with, or he needs to change".

Asked about these calls to step down in the interest of US-Ukraine relations, Zelensky said that to resign was one thing, but preventing him from running again would require Nato membership.

Ukraine joining the transatlantic military alliance has been a demand of Kyiv since the war began, and forms a key part of the country's victory plan - though the Trump administration has said this was unlikely.

"I am exchangeable for Nato," Zelensky told journalists before he was due to leave the UK.

"I have said that I am exchanging for Nato membership, which means I have fulfilled my mission. Nato means I have fulfilled my mission."

He added it was "not very democratic" for people from other nations to be deciding who led Ukraine, but said Graham could become Ukrainian, and then "his voice will have weight" in deciding who its leader was.