Madonna at the concert in Cardiff, Wales. (Reuters)

London, Aug. 26: Madonna has angered Senator John McCain, the US presidential candidate, by linking him to Adolf Hitler at the start of her world tour.

During Saturday night’s concert at Cardiff's Millennium Stadium, images of Hitler, Robert Mugabe, the Zimbabwe President, and McCain flashed up, along with scenes of global warming and devastation, at the start of the song Get Stupid.

As Madonna, 50, reached the end of the song pictures of John Lennon, Al Gore, the former US Vice-President, Mahatma Gandhi and Barack Obama — McCain’s Democrat rival — appeared on screen.

Tucker Bounds, the Republican Senator's campaign spokesman, said: “The comparisons are outrageous, unacceptable and crudely divisive all at the same time.

“It clearly shows that when it comes to supporting Barack Obama, his fellow worldwide celebrities refuse to consider any smear or attack off limits.”

Madonna appears to have transferred her allegiances to Obama after supporting Hillary Clinton during the campaign to choose the Democratic nominee. Other supporters include Robert de Niro, George Clooney, Matt Damon, Stevie Wonder and Oprah Winfrey. McCain’s campaign has sought to portray Obama, 47, as a celebrity with little substance. In one television advert his image appears alongside Paris Hilton and Britney Spears.