The wife of actor Mel Gibson has filed for divorce after 28 years of marriage, citing irreconcilable differences.

In divorce papers filed in Los Angeles Superior Court on Monday, Robyn Gibson asked for her 1980 marriage to the "Lethal Weapon" actor to be ended.

The couple, who have seven children, asked for privacy in a joint statement.

"Throughout our marriage and separation we have always strived to maintain the privacy and integrity of our family and will continue to do so," the statement said.

It was not clear how long the Gibsons have been separated but a report on the website for celebrity television show Entertainment Tonight said they had been living apart for almost three years.

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

Gibson, 53, a staunch Catholic, was raised in Australia and was one of the highest paid and most popular actors in the world in the 1990s, winning a best director and best picture Oscars for his 1995 movie "Braveheart".

He has adopted a lower public profile since his controversial 2004 hit movie "The Passion of the Christ" and his 2006 drunk driving arrest in Malibu when he launched into an alcohol-fueled tirade against Jews.