Los Angeles (Agencies): The custody battle between Halle Berry and ex-boyfriend Gabriel Aubry for their daughter Nahla is turning uglier amid accusations that the model used racial slur against the actress.

Aubry's former friend and business partner Stephane Bibeau claims the model became "verbally threatening" to Berry after they separated. Bibeau also accused the model of using a racial slur against the actress, the People magazine reported.

"He is a vindictive guy," Bibeau said. Celebrity website TMZ too has cited sources saying that Aubry addressed Berry with racial rants and other expletives both to her face and over text messages.

"He constantly demeaned her. It was awful," a source told the website.

Representatives for Aubry are yet to respond to the allegations. The model, however, had called Berry "irresponsible" in a statement recently.

But sources close to Aubry claim that he too has numerous emails, text messages and voicemails from Berry which "document her angry and jealous rages." The model is reportedly saving it to make his case strong in the court in the forthcoming custody battle.

The ex-lovers appeared to be amicably co-parenting to post their split in April but in December Aubry moved to court to be formally recognized as Nahla's father and to establish shared custody, prompting Berry to speed up the custody battle.

Berry, who dated Aubry for over five-years, is currently dating 'Unfaithful' star Olivier Martinez while Aubry was spotted out with Kim Kardashian but they denied romance.