Mariah Carey is "very friendly" with Brett Ratner's girlfriend.

Mariah Carey and Brett Ratner

Mariah Carey and Brett Ratner

The '#Beautiful' hitmaker, who split from Nick Cannon last summer after six years of marriage, recently sparked rumours she is dating the 'Hercules' producer after they were spotted strolling around St. Barts arm-in-arm.

But a source close to the duo insists the 46-year-old filmmaker's long-term girlfriend is also on holiday with them.

The insider told E! News: "Brett thinks it's silly. The woman he's dating was with them the whole time and is in half the pictures.

"It's not new. They've been casually dating for almost a year. She's very friendly with Mariah."

The 45-year-old singer has collaborated with Brett on music videos numerous times over the past two decades, but their relationship has always been platonic.

The source added: "Mariah would never think of Brett in that way. They're like brother and sister."

While Mariah, who has three-year-old twins Monroe and Moroccan with her estranged husband, has yet to start dating again, Nick, 34, is very happy with model Jessica White, 30.

A source previously said: "Jessica is completely smitten over Nick between his personality and good looks. She has been telling her close friends he makes her feel like she is on cloud nine and so loved. Nick is very affectionate with her when they are with each other."