The new US Supreme Court justice Brett Kavanaugh has been formally sworn in, with Donald Trump apologising to the judge for the fraught nomination process.

Mr Kavanaugh had been expected to be easily confirmed by the Senate, in which Republicans retain a small majority.

However, the process was derailed after he was accused of sexual misconduct, dating back when he was a teenager.

Accuser Christine Blasey Ford publicly testified about the allegations, and two more women also came forward with allegations.

However, despite a week-long delay to allow for an FBI investigation, Kavanaugh was ultimately confirmed for the lifetime position on Saturday with a 50-48 vote in the Senate along party lines - with only one senator from both the Democrats and Republicans voting against their party colleagues.

President Trump hosted Judge Kavanaugh and his family at the White House yesterday evening for a formal swearing in ceremony.

The US President told the judge: "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."

"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."

Earlier, Trump claimed the judge was "caught up in a hoax that was set up by the Democrats".

'Team player'

Judge Kavanaugh, meanwhile, acknowledged that the nomination process had been "contentious and emotional".

He said: "That process is over. My focus now is to be the best justice I can be.

"The Supreme Court is a team of nine and I will always be a team player on the team of nine."

Beyond the allegations, Democrats have expressed concern over the fact that Kavanaugh's lifetime appointment shifts the balance of the court to the right.

Senator Dianne Feinstein has suggested the confirmation puts "women’s reproductive rights, civil rights, environmental protections, worker’s rights, the ability to implement gun safety rules and the ability to hold presidents accountable at risk for a generation".

There has also been significant criticism of Kavanaugh's heated testimony before senators, which followed Dr Ford's testimony last month.

Judge Kavanaugh has himself acknowledged saying "a few things I should not have said".

Some Democrats have pledged to investigate the allegations about Kavanaugh further if they retake the House of Representatives or Senate in the upcoming midterm elections or the 2020 election.