Phillip Hancock was put to death by lethal injection at the Oklahoma State Penitentiary in McAlester, a spokesman for the Oklahoma department of corrections said.

The Oklahoma pardon and parole board had recommended that Hancock be granted clemency but it was denied by governor Kevin Stitt.

Hancock was sentenced to death for the April 2001 murders of Robert Jett and James Lynch, members of a biker gang.

Hancock claimed he shot Jett and Lynch during a struggle after they tried to force him into a cage at Jett’s Oklahoma City residence.

There have been 24 executions in the US this year.

No further executions are scheduled for the remainder of the year.

According to a recent Gallup poll, 53% of Americans support the death penalty for someone convicted of murder, the lowest level since 1972.

Capital punishment has been abolished in 23 US states, while three others – California, Oregon and Pennsylvania – have observed a moratorium on its use.

Executions have been carried out in five states this year: Alabama, Florida, Missouri, Oklahoma and Texas.

The death penalty has been primarily carried out by lethal injection in recent years, but Alabama intends to execute an inmate next year using nitrogen gas.

Alabama governor Kay Ivey has set Jan 25 as the execution date for Kenneth Smith, 58, who was sentenced to death for a 1988 murder.