An appeals court in the US state of Oklahoma has granted a last-minute stay of execution to death row inmate Richard Glossip so it can consider evidence that his lawyers say proves his innocence.

Glossip had been scheduled to die by lethal injection at 3:00 p.m. CDT (4 p.m. EDT) on Wednesday.

The Oklahoma Court of Criminal Appeals announced the two-week reprieve for the 52-year-old, who was sentenced to die for the 1997 fatal beating of a motel owner.

The court set the new execution date for September 30.

"In order for this court to give fair consideration to the materials included with his subsequent application for post-conviction relief, we hereby GRANT an emergency stay of execution for two weeks," the court order said.

Glossip, who has long proclaimed his innocence, has earned the support of many famous people, including actress Susan Sarandon and billionaire Richard Branson.

Earlier this week, Glossip's lawyers submitted new evidence, but Oklahoma Governor Mary Fallin said it was not "credible evidence" of his innocence and refused to suspend his execution.

"My office will respect whatever decision the court makes, as we have throughout this process," Fallin said after the stay was announced.

"As I have repeatedly said, court is the proper place for Richard Glossip and his legal team to argue the merits of his case," she added.

Glossip’s name is already synonymous with the problems plaguing US capital punishment. After the botched execution of Clayton Lockett in Oklahoma in April 2014, he and three other death-row inmates sued the Oklahoma State Department of Corrections in order to prevent their own executions with the controversial sedative midazolam.

The botched execution of Lockett in Oklahoma and other similar cases in Ohio and Arizona became very controversial in the US with human rights group calling for an end to the torturous killings.

According to the American Civil Liberties Union, the racial ratio of the victims of the death penalty in the US has been striking since the revival of the practice in 1976, with the penalty being disproportionately imposed on blacks and ethnic minorities.

Statistics released by the Texas Department of Criminal Justice show that 11 of the 16 executed prisoners in the state of Texas, which has been responsible for nearly 40 percent of all executions in the US since 1976, were African American or Hispanic in 2013.