Chris Brown has reportedly been "drunk-dialling" Rihanna.

The pair have a troubled relationship, which saw them split after he assaulted her in 2009 and then get back together, only to break up again several times.

Chris recently left prison, after being locked up for a probation violation due to being booted from an anger-management rehab.

"Chris has been drinking a lot since he left prison and drunk-dialled Rihanna a few times, trying to get in touch," a source told British magazine Heat.

Chris' on/off girlfriend Karrueche Tran supported him through his latest bout of personal problems, but they are now thought to have gone their separate ways. He posted a racy picture of her on Instagram, which showed her butt in just a thong. That is said to have upset her, with Karrueche also struggling to cope with the R&B's star's behaviour after he got out.

"Chris saw his opening when Ri ended things with Drake and couldn't help himself. But Karrueche found the evidence and confronted him," the insider explained.

"She blames the boozing and has been trying to clamp down on it after he was carried out of a club last week. She told him she'd dump him unless he went back to rehab, but he won't."

Rihanna's romance with Drake has also been an on-going saga, but they aren't thought to be together at the moment. She has apparently spoken to her family and friends about Chris and is choosing to listen to one of their pieces of advice in particular.

"Ri had lunch with her dad Ron in LA recently and he told her to give Chris another chance," the source said. "Everyone else has been telling her not to, but Rihanna can't resist. She texted Chris back and has been flirting a fair bit since."

Earlier this week Karrueche broke down during a TV interview about her love life, where she spoke about how hard Chris' relationship with Rihanna has been on her.

"Even the situation with Rihanna, you know the reason why people tuned into this so much was because it's relatable. I have girlfriends; I have family who's gone through the same situation. It's the case of the ex. We all go through it, do you know what I'm saying," she explained.

"In this case, my boyfriend is a celebrity whose ex-girlfriend is an even bigger [celebrity]... so, not only am I fighting a battle with her, I'm fighting a battle with her 14 million fans or whoever else."