Madonna and Lady GaGa are in talks to appear on the forthcoming series of The X Factor, according to reports.

Rihanna has also apparently been approached about appearing on the talent contest, which gets under way later this year.

The trio would follow in the footsteps of such acts as Britney Spears, Beyonce and Take That, who have all mentored X Factor contestants in previous series.

"The last series proved anything is possible when Beyonce performed with (eventual winner) Alex,” a source told The Sun newspaper.

“The final got 15 million viewers and that is enough to entice the biggest stars on to our stage.

"This year is going to be bigger than ever – we are planning to get the best names in music. Madonna and Robbie would be sensational."

The 2009 series is due to begin on ITV in August.

Lady GaGa's crazy style