Brett Kavanaugh seeks new tone after Supreme Court fight; Trump apologises for process

US Supreme Court Justice Brett Kavanaugh sought to put a bruising confirmation battle behind him on Monday at a White House ceremony in which President Donald Trump declared him innocent of sexual misconduct and apologised for the heated process.

"On behalf of our nation, I want to apologise to Brett and the entire Kavanaugh family for the terrible pain and suffering you have been forced to endure," Trump said at the start of a ceremonial swearing-in in the East Room of the White House.

"Those who step forward to serve our country deserve a fair and dignified evaluation, not a campaign of political and personal destruction based on lies and deception," he said.

Kavanaugh's confirmation process exploded in controversy after California university professor Christine Blasey Ford went public with allegations that Kavanaugh sexually assaulted her in 1982, while they were in high school.

Kavanaugh gave a forceful, emotional denial of those allegations during testimony before lawmakers that some Democrats said showed a lack of judicial temperament. The US Senate voted 50-48 on Saturday to confirm him, with just one Democrat supporting him.

Kavanaugh said on Monday that he was starting his new job without bitterness, seeking to set a new tone after the divisive process.

"The Senate confirmation process was contentious and emotional. That process is over. My focus now is to be the best justice I can be," he said with his wife and children standing nearby.

He said he would aim to be a force for stability and unity on the court, whose other eight members all attended the White House ceremony.

"Although the Senate confirmation process tested me as it has tested others, it did not change me," he said.