OKLAHOMA, Oct 28 ― Oklahoma must postpone the executions of condemned inmates John Grant and Julius Jones while a legal challenge to the state's lethal injection protocol is adjudicated, a US appeals court panel ruled yesterday.

The execution of Grant, which was scheduled for 4pm today, will now go forward only if the US Supreme Court overturns the ruling by a three-judge panel of the 10th US Circuit Court of Appeals.

Oklahoma will appeal the ruling to the Supreme Court, local media reported, citing a statement from Oklahoma Attorney General John O'Connor's office.

Grant, 60, was sentenced to death for killing a prison employee, and Jones, 41, for murdering an insurance executive gunned down in his driveway. Jones has maintained his innocence for two decades in a case that has attracted attention from celebrities and anti-death penalty activists.

In ordering the state to delay putting to death Grant and Jones, whose execution was to be held on November 28, the judges said a lower court had unfairly denied the two men delays granted to numerous other defendants pursuing a lawsuit challenging the constitutionality of the state's three-drug lethal injection protocol.

Opponents of the method say it could result in a prolonged and painful death in violation of the Constitution's protection against cruel and unusual punishment.

"They risk being unable to present what may be a viable Eighth Amendment claim to the federal courts before they are executed using the method they have challenged,” the judges wrote.

Dale Baich, an attorney for the condemned men, welcomed the ruling, saying in a statement: "Today’s order should prevent the State from carrying out executions until the federal district court addresses the 'credible expert criticism' it identified in Oklahoma’s execution procedures. Those issues will be carefully reviewed by the court at the trial scheduled in February.”

The Oklahoma attorney general's office said in a statement provided to Oklahoma City television station KWTV-DT: "We are hopeful that the Supreme Court will vacate the stay so that justice can finally be served for the people of Oklahoma, including the families of the victims of these horrific crimes.”

Thirty-six US states and the District of Columbia have either abolished the death penalty or not carried out an execution in the past 10 years, according to the Death Penalty Information Center.

Oklahoma has not conducted an execution in six years, since three botched attempts ending with the death of Charles Frederick Warner in 2015. Warner, who was convicted of the rape and murder of an 11-month-old girl, was executed using the wrong drug, officials said later.

The previous year, Clayton Lockett, convicted of murder, rape and kidnapping, regained consciousness and raised his head after the execution procedure began, only to die in apparent anguish less than an hour later, court records show. ― Reuters