Mel Gibson 'admits to Grigorieva slap'

Mel Gibson has reportedly admitted to slapping ex-partner Oksana Grigorieva in a sworn statement.

According to TMZ, the actor gave a sworn declaration dated June 23 in which he concedes that he slapped Grigorieva during an incident on January 6.

However, Gibson denies hitting his then-girlfriend and insists that he only struck her in order to stop her from "erratically" shaking their daughter Lucia as they argued.

The declaration states that Grigorieva lifted their baby daughter out of her bassinet during a disagreement and ran into the garden, which is dangerous at night due to rough terrain.

Gibson claims that Grigorieva then returned to the house and "started swinging Lucia erratically in her arms, jerking her body from side to side to keep Lucia out of [his] reach".

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."

The website says that Gibson's account could support a defence of "using reasonable force to protect a child from injury" in any domestic violence charge.