Rihanna treats friends to a 'world of total indulgence' when she invites them on holiday.

The singer enjoyed a girls-only vacation as she hired a £50 million yacht on the French Riviera last week.

Rihanna asked model-of-the-moment Cara Delevingne, her stylist and friends, including Melissa George, to party with her on the lavish trip.

'When Rihanna charters a super-yacht for her mates, she pays for everything from the moment you arrive, she makes sure it's a world of total indulgence,' a source told British magazine Grazia. 'Every morning she wakes everyone up with champagne breakfast in bed and the partying goes on all day long.

In the first 36 hours, Rihanna, Cara and their group apparently enjoyed three bottles of tequila, a case of Dom Pérignon and a £300 bottle of bourbon.

The R&B star is even reported to have hired a nurse to administer vitamin shots to her guests to help with hangovers.

'Rihanna swears by vitamin drips and injections,' a source explained. 'So she ensured she had a nurse on hand to dispense vitamin injections to give everyone a boost when they'd overindulged.'

During their time on the yacht, the girls took a break from partying to enjoy doughnut rides, parascending and jet-skiing.

Cara was thrilled to take a break from her usual routine and relax with Rihanna. The British model is believed to be going through a tough time at the moment, after her close friendship with Rita Ora hit a rocky patch.

'Cara and Rita have hardly seen each other in recent weeks and Cara's been feeling pretty down. A girly holiday with Rihanna was exactly what she needed. Rihanna's been through her own heartache with Chris Brown, so they would often stay up late into the night chatting. They've become really close.'

It has been reported that Rihanna has invited Cara to spend a long weekend at her home in Barbados next.