Kim Hjelmgaard, and Lorena Blas

USA TODAY

Brad Pitt is being investigated after being accused of verbal and physical abuse against his children.

Los Angeles County Department of Children and Family Services spokesman Armand Montiel told USA TODAY by law the agency cannot confirm or deny investigations.

But a source close to Pitt, who was not authorized to speak publicly, told USA TODAY that Pitt is taking this matter "very seriously and is fully cooperating."

"The claims are greatly exaggerated or fabricated," the source said. "But he’ll always do whatever is best for his kids. Despite being on the receiving end of an onslaught of allegations, he remains focused on doing whatever is best for the children.”

Source: Claims that Pitt abused kids are 'exaggerated or fabricated'

TMZ reports the actor, whose wife Angelina Jolie filed for divorce Monday, is under investigation following an incident on a private jet.

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TMZ says the case was referred over to the FBI on Thursday due to the fact that the alleged incident happened in the air while the family was on a plane from France last Wednesday.

“The FBI is continuing to gather facts and will evaluate whether an investigation at the federal level will be pursued,” FBI spokeswoman Laura Eimiller said in a statement emailed to USA TODAY.

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In divorce documents, Jolie listed the couple's date of separation as the following day, Sept. 15.

People.com reports that Pitt is accused of getting verbally abusive with one of couple's kids, as well as getting physical while the family was on their private plane. People and TMZ both note that Jolie and at least some of the couple's other children were present at the time. Pitt and Jolie have six children: Maddox, 15, Pax, 12, Zahara, 11, Shiloh, 10, and twins Vivienne and Knox, 8.

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The Los Angeles Police Department is so far not investigating. "LAPD is not handling any report or allegations into child abuse against Brad Pitt," spokeswoman Officer Jenny Houser told USA TODAY in a statement on Thursday.

Attempts to reach Jolie's representative were not successful.

Contributing: Maria Puente, Andrea Mandell