THE wife of actor Mel Gibson has filed for divorce after 28 years of marriage.

In divorce papers filed in Los Angeles Superior Court, Robyn Gibson asked for her 1980 marriage to the Lethal Weapon actor to be ended. The couple have seven children.

The move comes just weeks ater Gibson was pictured frolicking on a beach in Costa Rica with an unidentified brunette. His wife could be due half his £640million fortune.

In a joint statement, the Gibsons said: "Throughout our marriage and separation we've always strived to maintain the privacy of our family and will continue to do so."

The actor and director of movies, including What Women Want, filed a response saying the two had been separated since August, 2006.

Weeks earlier, Gibson had been arrested in Malibu for drunken driving and launched into an alcohol-fuelled tirade against Jews.

It was reported that Gibson also cited irreconcilable differences as the reason for the split.

Six of the couple's children are adults. Robyn Gibson asked for joint custody of the only minor, Tom, who turns 10 on Tuesday.

Mel, 53, won best director and best picture Oscars for his 1995 movie Braveheart.