Robbie Williams has become good friends with Princess Beatrice and refers to her as "sis", according to reports.

The Take That star apparently hit it off with the 22-year-old royal after being introduced by her mother, Sarah Ferguson.

A source said: "Robbie gets on really well with Beatrice. He treats her like a little sister and looks after her. It's really sweet."

Fergie first met Williams on holiday in the Caribbean in January and has become a regular visitor at his and wife Ayda Field's home in Los Angeles, reports The Sun.

The pair are said by friends to get on "like a house on fire".

Williams is currently preparing to hit the road with Take That on their first tour since he rejoined the group last year.

(by Jason Gregory)