Supreme Court nominee Brett Kavanaugh, listens to Sen. Cory Booker, D-N.J. speak during a Senate Judiciary Committee nominations hearing on Capitol Hill in Washington. (AP Photo/Manuel Balce Ceneta, File)

Washington - US President Donald Trump defended embattled Supreme Court nominee Brett Kavanaugh Monday, but said that the appeals court judge has had a "bit of difficulty" with alcohol.

Trump called Kavanaugh's treatment unfair, days after the FBI opened a Senate-requested probe into allegations by three women that a drunken Kavanaugh sexually abused them while they were students in the 1980s.

In a White House press conference, Trump sought to excuse excessive drinking by teenagers, while going beyond Kavanaugh's own testimony on his past use of alcohol to the Senate Judiciary Committee last Thursday.

"I was surprised at how vocal he was about the fact that he likes beer," the president said.

"He's had a little bit of difficulty. He talked about things that happened when he drank. This is not a man that said ... he was perfect with respect to alcohol."

He questioned why investigators needed to examine the 53-year-old Kavanaugh's high school record.

"I think it's very unfair to bring up things like this," Trump said.

"I graduated from high school and while I did not drink, I saw a lot of people drinking," he said.

"They drink beer and go crazy and they were in high school ... Does that mean that they can't do something they want to do in their life?"

- 'I like beer' -
Testifying before the Senate Judiciary Committee on Thursday, Kavanaugh vehemently denied the sexual abuse allegations, and also aggressively challenged suggestions he had an alcohol problem at the time.

"I drank beer with my friends. Sometimes I had too many beers," he told the panel.  

"Yes, we drank beer. I liked beer. I still like beer," he said.

"If every American who drinks beer or every American who drank beer in high school is suddenly presumed guilty of sexual assault, it will be an ugly, new place in this country."

Trump meanwhile said the White House would not restrict the new FBI probe,  requested by the Senate before they take a final vote on the nominee.

"I think the FBI should do what they have to do to get to the answer," Trump said.

"I want it to be comprehensive ... With that being said, I would like to go quickly."

"We don't want to go on a witch hunt, do we?"