President Barack Obama is to nominate veteran appeals court judge Merrick Garland to be the next US Supreme Court Justice, White House officials say.

The Supreme Court vacancy follows the death of Justice Antonin Scalia last month at the age of 79.

Judge Garland, 63, is the chief judge of the Washington appeals court and a former prosecutor.

The Republican majority in the Senate has said it will block a vote on any Supreme Court nominee from Mr Obama.

The death of Scalia, a staunch conservative, left the nine-member Supreme Court evenly divided between conservatives and liberals.

It also set off a battle in a presidential election year over his successor.

Merrick Garland was appointed by Democratic President Bill Clinton in 1997, winning confirmation in a 76-23 vote, and served in the Justice Department during the Clinton administration prior to that.

One White House official quoted by Reuters news agency said: "No-one is better suited to immediately serve on the Supreme Court."

Merrick Garland: Profile of US Supreme Court hopeful

Veteran appeals court judge Merrick Garland is President Barack Obama's nominee to the US Supreme Court. If successful, he would replace conservative Justice Antonin Scalia, who died in February. Who is Merrick Garland?

Judge Garland, 63, is the chief judge of the Washington appeals court and a former prosecutor. The Harvard graduate would be the oldest candidate nominated for the Supreme Court since the 1970s.

He was appointed by Democratic President Bill Clinton in 1997, winning confirmation in a 76-23 Senate vote. Before that, he served in the Justice Department during the Clinton administration.

He has a moderate record and a history of drawing Republican support, which may be why he has been chosen in an election year with the Senate under Republican control.

Like Justice Scalia, Judge Garland has significant prosecutorial experience and is seen as having a relatively harsh record on criminal justice.

A profile on SCOTUS Blog which follows Supreme Court developments, says he "rarely votes in favor of criminal defendants' appeals of their convictions".

The judge was under consideration in 2009 for President Obama's first Supreme Court nomination appointment but the president chose Sonia Sotomayor.