Rihanna has been secretly hooking up with ex-boyfriend Chris Brown for almost a year, sources have claimed.

The former couple split three years ago after an argument turned violent. Chris was charged with assaulting the pop beauty and served with a restraining order.

However, reports have been circulating that Rihanna has found it hard to move on following the messy split - despite being linked to a number of other men. A music industry insider has claimed that the ex-lovers have rekindled their romance and have been meeting up regularly over the past twelve months.

"[They] meet up very casually. She comes to see him anytime she's in L.A.," the source told American publication US Weekly. "They can't get enough of each other. I don't see it ending well."

Speculation has been mounting whether the We Found Love singer has been in touch with her ex again after she exchanged a number of tweets with Chris. Friends and family are said to be understandably concerned about a potential reunion.

"Rihanna loves to live dangerously, and talking to and hooking up with Chris is all part of that," a Rihanna insider added.

Chris' spokesperson denied that the pair are back together, not least because the Forever singer is dating model Karrueche Tran.

"He and Rihanna are just friends," Brown's rep tells Us. "He's not cheating."