AceShowbiz - Mel Gibson has allegedly admitted slapping ex-girlfriend Oksana Grigorieva - but insists he was trying to stop her behaving "erratically" around their baby daughter, according to court papers. The "Braveheart" star is currently locked in a bitter custody battle with Grigorieva, who claims he hit her and knocked out her teeth during an alleged altercation in January.

The claims sparked a domestic violence investigation and the Russian singer told police she was holding baby Lucia at the time of the incident. Newly obtained court papers, dated June 23 and obtained by TMZ.com, reportedly state Gibson admitted striking Grigorieva once at their Malibu, California home - but the actor insists it was necessary to calm his "hysterical" partner.

Gibson claims he and his ex were arguing when Grigorieva took their baby out of her bassinet and "spun around", taking her into their darkened backyard. She is said to have eventually brought the tot back inside before running into her son Alexander's bedroom and "swinging Lucia erratically in her arms, jerking her body from side to side to keep Lucia out of my (Gibson's) reach".

Gibson claims Grigorieva's "rapid movements were causing Lucia's little body to be flung from one side to the other, her head shaking violently". He adds, "I slapped Oksana one time with an open hand in an attempt to bring her back to reality. I did not slap her hard, I was just trying to shock her so that she would stop screaming, continuing shaking Lucia back and forth."

"I did not hit Oksana with a closed fist, as she alleges. I did not ever punch her in the face or in the temple or anywhere else, not then or at any other time. While I do not believe I handled the situation as well as I should have, I was worried about the rough way Oksana was shaking and tossing Lucia around. My hand never touched any part of Lucia."

"There was never any blood on Oksana and none of her teeth were 'broken,' although one of the false veneers from a tooth apparently did come off, I did not see that occur at the time." Grigorieva is set to open up about the incident and her time with Gibson in a candid chat on American show "Larry King Live", after reportedly recording an interview with the host at the weekend.