Madonna and David Beckham's sons are forecast to become the richest celebrities in Britain.

Youngsters Rocco Ritchie, nine, and Cruz Beckham, four, are tipped to have the most earning power in a new report which assessed the estimated worth of today's celebrity children in 20 years time.

Rocco, son of the 'Celebration' singer and film director Guy Ritchie, topped the four categories in the report - star quality, likely inheritance, talent and love of the camera - getting ratings of ten out of ten for each.

The report also estimated Rocco to be worth £376 million before he reaches 30.

Celebrity expert Mark Frith said: "Rocco will earn a fortune from his mother and a fair bit from dad. But it's the other three rankings that power him to the number one place."

Cruz - whose mother is former Spice Girl turned fashion designer Victoria Beckham - beat siblings Romeo, seven, and Brooklyn, ten, to second place in the list.

Both Rocco and Cruz scored highly because they have been spotted dancing at their mother's concerts.

None of Rocco's other siblings - sister Lourdes and adopted brother and sister David and Mercy - featured on the list.

British royals, Princes William and Harry, came ninth and tenth on the list - compiled by Cartoon Network - with estimated fortunes of just under £200 million each, but were both embarrassingly awarded zero out of ten for showbiz talent.

Cartoon Network's Power Pups of the Future, top ten future celebs:

1. Rocco Ritchie £376 million

2. Cruz Beckham £341 million

3. Damian Hurley £330 million

4. Coco Sumner £315 million

5. Lizzy Jagger £310 million

6. Junior Andre £302 million

7. Romeo Beckham £271 million

8. Brooklyn Beckham £251 million

9. Prince Harry Wales £198 million

10. Prince William Wales £178 million