US President Joe Biden made another blunder at the final event of the NATO Summit – accidentally calling Ukraine's President Volodymyr Zelensky Vladimir Putin.

The extraordinary error happened ahead of his highstakes solo press conference this hour.

"And now I want to hand it over to the President of Ukraine, who has as much courage as has determination, ladies and gentlemen, President Putin," Mr Biden said.

"President Putin, he's a big President Putin, President Zelensky. I'm so focused on beating Putin that we have got to worry about it – anyway."