Brad Pitt Files for Joint Custody of 6 Children With Angelina Jolie

— -- Brad Pitt wants joint custody of his six children with estranged wife Angelina Jolie.

A rep for the actor confirmed to ABC News that Pitt, 52, filed legal documents Friday asking a judge for custody rights.

This comes after Jolie, 41, asked for sole physical custody of the children, according to her Sept. 20 petition to end their marriage, which was obtained by ABC News.

The duo, who became a couple in the mid-2000s, have six children: Maddox, 15, Pax, 12, Zahara, 11, Shiloh, 10, and twins Knox and Vivienne, 8. The couple tied the knot in 2014 after almost a decade together.

Pitt's request for joint custody comes amid an investigation by authorities of child abuse, involving one or more of his kids, sources told ABC News. The investigation began back in September after an alleged incident aboard a flight from France to Minnesota to Los Angeles. Authorities were trying to determine which child or children was involved and if the alleged incident was physical or just verbal, a source said.

Sources close to Pitt told ABC News that the actor is taking the allegations very seriously and cooperating with authorities. However, they added, many of the claims made against him are either exaggerated or outright fabricated.

"I am very saddened by this, but what matters most now is the well-being of our kids," Pitt said back in September.

The actor has not yet responded to the abuse allegation, though sources told ABC News that his number one priority remains the welfare of the children.