Rihanna has recruited her abusive ex-boyfriend Chris Brown to make a guest appearance on the remix of her new single, according to reports.

The former couple has allegedly reunited in the studio for the release of "Birthday Cake," three years after Brown was arrested and charged for assaulting Rihanna on the eve of the 2009 Grammy Awards.

The altercation landed Brown a conviction and saw him sentenced to hard labor, while he was also ordered to stay away from the "Umbrella" hitmaker.

The restraining order has since been relaxed, and it appears Rihanna has forgiven the controversial singer - and invited him to lay down vocals for the extended version of "Birthday Cake," a catchy interlude from her latest album "Talk That Talk."

Producers Da Internz recently fuelled rumors of Brown's involvement, telling MTV News, "It's gonna be crazy. And the feature on there is gonna shock the world."

Rihanna's Twitter posts have done little to dispel the gossip after quoting defiant lyrics from her 2010 song Hard.

After news of the collaboration surfaced on Friday, she tweeted, "They can say whatever, Ima (sic) do whatever... No pain is forever, YUP! YOU KNOW THIS."

And a representative for Brown tells Life & Style magazine, "Chris and Rihanna are friends again."

The publication reports the track will be released next week.

Brown has been courting controversy again since performing at the Grammys last Sunday, when his presence and Best R&B Album win upset many celebrities and music fans on the third anniversary of his Rihanna fall-out.