The 'You Da One' singer, who recently blew up at her former boyfriend on Twitter, has allegedly been meeting with Brown for almost a year.
"[They] meet up very casually," an insider told Us Weekly. "She comes to see him anytime she's in LA."
Another source predicted that the rumoured relationship will not last.
"They can't get enough of each other," the second insider said. "I don't see it ending well."
However, a rep for Brown has denied the reports, insisting that he is not cheating on girlfriend Karrueche Tran.
"He and Rihanna are just friends," the rep said. "He's not cheating."
Earlier this month, it was reported that Rihanna hoped to reconcile with Brown. The singer previously claimed that she would never speak to Brown again.
Watch the video for Rihanna's 'You Da One' below: