Rihanna in secret dates with ex Brown?

Rihanna and her ex-boyfriend Chris Brown have allegedly been secretly hooking up.

The 24-year-old pop beauty collaborated with the R&B star - who was convicted for assaulting the 'Russian Roulette' hitmaker in 2009 - on her latest single 'Birthday Cake' and the pair have reportedly rekindled their romance, which has left Rihanna's friend and mentor Jay-Z "deeply disgusted".