US President Trump has named conservative appeals court judge Neil Gorsuch as his nominee to take the vacant seat on the United States' highest court.

At 49, Gorsuch is the youngest Supreme Court nominee in 25 years.

The nomination will have to be approved by the Senate.

If confirmed he will replace the vacancy left on the high court by Justice Antonin Scalia, who died in February 2016.

Democrats have previously said they will block any nomination seen as too conservative.

"Judge Gorsuch has outstanding legal skills, a brilliant mind, tremendous discipline and has earned bipartisan support," said Mr Trump.

He announced the nomination in his first televised prime-time address from the White House.

Trump took care to praise the late Justice Antonin Scalia as did Gorsuch calling him a "lion of the law".

Gorsuch thanked Trump for entrusting him with "a most solemn assignment."

He added: "Standing here in a house of history, I'm acutely aware of my own imperfections and pledge that if I am confirmed, I will do all my powers permitted to be a faithful servant of the Constitution of laws of this great country."

The Supreme Court nomination arguably marks the most significant decision of Trump's presidency to date, one with consequences that could last after he leaves office.

For some Republicans, the idea of filling one or more Supreme Court seats over the next four years has helped ease their concerns about Trump's experience and temperament.

Three justices are in their late 70s and early 80s, and a retirement would offer Trump the opportunity to cement conservative dominance of the court for many years.

If Democrats decide to block Gorsuch's nomination, his fate could rest in the hands of Senate Majority Leader Mitch McConnell.

Trump has encouraged McConnell to change the rules of the Senate and make it impossible to block a Supreme Court nominee, a change known in the Senate as the "nuclear option".