Up to 10 million viewers are expected to see her appearance on the hit daytime programme with Oprah

The 48 year-old singer will appear, via satellite, on the special episode of Oprah, called The World’s Got Talent.

However, Simon Cowell and producers of the ITV talent show want Boyle to save her voice for the semi finals, according to reports.

They are also reportedly concerned that rivals will think the appearance on the US chat show will give her an unfair advantage.

Up to 10 million viewers are expected to see her appearance on the hit daytime programme.

The special show will feature acts from some of the 40 countries where the show is filmed, including last years Britain’s Got Talent contestants, Signature.

Cowell is also expected to be interviewed by Oprah, according to The Daily Mirror.

Boyle has been watched by millions of internet viewers since she first stunned judges with her rendition of I Dreamed A Dream from the musical Les Misèrables.

It has turned her into a global phenomenon with celebrity fans including the actress Demi Moore.

She has already appeared on several US TV programmes including Larry King Live, the veteran interviewer’s CNN show.

Boyle remains favourite to win Britain’s Got Talent but faces competition from fellow singer Jamie Pugh, the Welsh pizza delivery man who overcame stage fright to sing a tune from Les Misèrables. However, his chances were dealt a blow when it was disclosed that he had sung in a West End theatre before, contradicting his claim that he had never performed before a large crowd.