Brad Pitt volunteered for drug and alcohol test during investigation into alleged incident between him and son

The 'Troy' actor is said to have volunteered to do the test to clear up any "exaggerations", but the Department of Children & Family Services did not require it to be carried out.

The results are not yet known.

This comes just days after it was reported it is highly unlikely Brad will be prosecuted for the abuse allegations because conflicting accounts make it impossible to prove what happened.

According to the publication: "DCFS [Department of Children & Family Services] social workers saw no evidence of injuries on Maddox and no one filed a police report after the incident."

Sources close to Brad have previously insisted that allegations of abuse against him are "exaggerated and fabricated" with sources close to the actor hitting out at the "smear campaign" against him.

A source said: "These claims are exaggerated and fabricated.

"It's unfortunate for the whole family that people are insisting on continuing this endless smear campaign against Brad that hurts everyone.

"They are a solid family with two caring parents and a normal share of verbal disagreements like major households.

"Hopefully people can move on and leave them all alone to work this out."

It has been claimed that Maddox stepped in when a row between Brad and his now-estranged wife Angelina Jolie became got heated on board a private plane from France to Los Angeles earlier this month.

Angelina filed for divorce from Brad last week after 12 years together.

The couple also have kids Pax, 12, Zahara, 11, Shiloh, 10, and twins Knox and Vivienne, eight.