Image source, Oklahoma Department of CorrectionsImage caption, Julius Jones maintains his innocence

Hundreds of students walked out of school on Wednesday in a final attempt to persuade the governor of the US state of Oklahoma to grant clemency to a death-row inmate who is scheduled to be executed on Thursday.

In 2002, Julius Jones was sentenced to death for killing Paul Howell during a carjacking three years earlier.

Mr Jones, 41, maintains his innocence.

His case has attracted the support of celebrities and anti-death penalty activists.

Mr Jones's execution by lethal injection is scheduled for 4 pm local time (2200 GMT) at the state penitentiary in McAlester.

His last hope for clemency rests with Republican Oklahoma Governor Kevin Stitt.

The governor is yet to rule on a recommendation on a 3-1 vote by the state's Pardon and Parole Board that his sentence be commuted to life in prison with the possibility of parole.

The case has attracted widespread attention in recent years, partly due to the 2018 ABC documentary series "The Last Defense".

More than 6 million people have signed a Justice for Julius petition which states he was put on death row because of "fundamental breakdowns in the system tasked with deciding".

On Wednesday morning, students from several Oklahoma City high schools left their lessons in support of Mr Jones's clemency.

Mr Jones was found guilty of fatally shooting Mr Howell, an insurance executive, during a 1999 carjacking on his driveway.

In October, he was among five people who won stays of execution from a three-judge panel of the 10th Circuit US Court of Appeal.

"I did not kill Mr Howell," he wrote in a letter to the parole board in April, after exhausting his appeals.

"I did not participate in any way in his murder; and the first time I saw him was on television when his death was reported."

But Mr Howell's relatives say Mr Jones's calls for clemency have victimised them further.

His appeal has drawn attention from some high-profile figures, including reality TV star Kim Kardashian, who has long advocated against Mr Jones's death sentence.