Madonna paid tribute to Michael Jackson as she described him as one of the greatest performers the world has ever known.

A huge picture of Jackson as a child was beamed above the stage during a short dance melody dedicated to the star as the Queen of Pop performed at the O2 Arena in London.

One of her dancers dressed in Jackson's trademark black hat moonwalked across the stage to the delight of the huge crowd packed into the arena.

Short versions of two of Jackson's greatest hits, Billie Jean and Wanna Be Startin Somethin, were also performed.

Madonna then turned to the crowd and said: "To one of the greatest performers the world has ever known - Michael Jackson."

Jackson had been due to perform 50 concerts at the O2 Arena starting later this month.

The star died on June 25 after suffering a suspected cardiac arrest.

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