Brown in vulgar Twitter feud over Rihanna

Chris Brown has slammed a comedy writer for bringing up his assault of ex-girlfriend Rihanna in a vulgar Twitter rant.

The Kiss Kiss hitmaker was convicted of the crime in 2009 but the stars have been working on their friendship in recent months.

Jenny Johnson took to the micro-blogging website on Sunday, inciting vitriol from Chris after she re-tweeted his post about looking old for his age.

"I know! Being a worthless piece of s*** can really age a person," she wrote.

"Take them teeth out when u Sucking my d*** HOE," he responded.

Jenny took the opportunity to correct his spelling and said that his mother must be proud.

Chris responded by calling her "worthless" and a "thirsty b****". He later claimed he was joking.

"Just ask Rihanna if she mad??????" he wrote.

Jenny told the 23-year-old to get help. She signed off with a summary of her feelings on the exchange.

"I have zero respect for a person who seems unapologetic for the terrible crime he committed and shows no signs of changing," she wrote.

The remarks came a day after Rihanna tweeted a photo of Chris shirtless appearing to sleep on a bed.

The pair were also spotted together at a nightclub in Berlin on Thursday.

Chris broke up with girlfriend Karrueche Tran last month.

Both Chris and Rihanna have denied they are romantically involved despite being seen together several times since the split.