Rishi Sunak is "disappointed" Ukrainian President Volodymyr Zelensky has not been allowed to address this year's Eurovision, his spokesman says.
EDnews informs via CNN that the organisers, the European Broadcasting Union (EBU), say it would breach its political impartiality.
But Downing Street said it would be "fitting" for Mr Zelensky to speak given Russia's invasion of his country.
Labour leader Sir Keir Starmer is also calling for the Ukrainian leader to be allowed to make a speech.
Ukraine was meant to be hosting this year's Eurovision after winning it last year, but it is taking place in Liverpool instead after Russia's invasion.
It has been reported that Mr Zelensky wanted to make a video appearance at the contest's final on Saturday, to an expected global audience of 160 million.