LOS ANGELES, July 15, 2010 (AFP) – Mel Gibson was embroiled in a battle with his ex-girlfriend Thursday over custody of their baby girl, an entertainment website said, as recordings of his alleged obscenity-filled rages went viral.

TMZ.com said the actor-director and the Russian-born model and pianist Oksana Grigorieva were attending the hearing behind closed doors.

The website said the hearing was likely to consider the audio tapes, allegedly of Gibson threatening and cursing Grigorieva, and that attorneys for the mother would argue the rants are evidence that Gibson is a danger to their child, Lucia.

But Gibson's lawyers were to counter the tapes had been altered and planned to present forensic evidence showing tampering, according to TMZ.

The judge in the case will first have to decide whether the tapes are even admissible in court.

TMZ said Grigorieva's lawyers would be asking the judge to strip Gibson, 54, of custody of the couple's daughter, who was born last October.

The hearing comes with Gibson's legal and career problems mounting from the release of profane and rage-filled comments on the celebrity gossip website RadarOnline.com.

The Los Angeles County Sheriff's Department has confirmed the actor is under investigation for alleged domestic abuse. Gibson is to appear in court next Tuesday in the domestic violence case.

In the past week, the audio recordings allegedly feature the Oscar-winning "Braveheart" director using racial language to disparage a Hispanic cleaning lady. In earlier tapes Gibson referred to black people as "niggers," called Grigorieva a "whore" and a "bitch in heat," and apparently acknowledges beating her.

While they have not been authenticated, Gibson has not issued any denial since they began surfacing on Friday.

The tapes conclude the ugly breakup between Grigorieva, 40, and Gibson, following a January 6 beating she allegedly took from him. Gibson is accused of knocking out some of Grigorieva's teeth in the fracas.

Gibson had seven children with his former wife Robyn in a 30-year marriage before they divorced last year.