Rihanna wants to give Cara Delevingne a self-portrait as a sign of their friendship.

The 25-year-old singer has commissioned street artist Bambi to create a giant painting of her best friend as a present for the supermodel and her family.

A source told the Daily Star newspaper: ''Rihanna wanted to show Cara how important their friendship is to her. It will be a gift for both her and her family.

''Bambi came up with the concept, which is inspired by Andy Warhol's famous image of Debbie Harry, and Rihanna loves it.

''She even asked Bambi to do the painting on an old piece of metal, so it looks completely unique and quirky. The artwork is yet to be delivered but will go straight to Cara's family home where it will probably stay.''

The 'Diamonds' hitmaker was able to contact the artist - whose identity has been kept a secret - because she knows the mysterious pop star personally.

And despite the painting carrying a big price tag, Rihanna is said to be willing to pay for the special gift.

The insider added: ''The painting will cost around five figures but Rihanna doesn't mind spending that. Cara's one of her closest allies.''