Columbia, South Carolina – South Carolina has introduced firing squads to the US state's execution methods amid a lack of lethal-injection drugs.

"This weekend, I signed legislation into law that will allow the state to carry out a death sentence," Republican Governor Henry McMaster on Monday.

"The families and loved ones of victims are owed closure and justice by law. Now, we can provide it," he tweeted.

The south-eastern state's lower and upper house last week voted to approve the bill, which will require inmates on death row to choose to die by firing squad or electric chair if injection drugs aren't available.

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South Carolina has not executed any inmates in a decade, having had to postpone three executions due to a nationwide shortage of lethal injection drugs, according to local newspaper the State.

In February, Virginia became the first state in the South to stop executions.

The death penalty is on the decline in the United States, in part due to changing public opinion, as well as the increasing difficulties in obtaining the necessary substances for lethal injections.

The imposition of the death penalty also usually leads to protracted and costly litigation.

In 2020, a total of 17 people were executed in the US by five states and the federal government, according to the Death Penalty Information Center.