Arkansas has acquired a new supply of a drug needed for its lethal injections ahead of next month's scheduled executions of eight men over four nights, a state corrections spokesman said on Monday.

Arkansas, which has not put an inmate to death since 2005, is one of several states where executions have been on hold because of legal battles and problems in procuring lethal injection drugs after a sales ban by major pharmaceutical makers.

The state’s stock of potassium chloride expired on Jan. 31. Republican Governor Asa Hutchinson signed an order for the executions about a month later, despite the lack of the drug.

A new batch of the drug arrived in the state last Wednesday, Arkansas Department of Correction spokesman Solomon Graves said by phone. He would not disclose how the state got it, citing an Arkansas law prohibiting disclosure of the source of drugs used for executions.

“I can confirm that we have obtained an additional amount of potassium chloride sufficient to carry out the executions scheduled by the governor,” Graves said.

A spokesman for the governor said Hutchinson had maintained confidence in the correction department's ability to procure the drug.

Hutchinson acted after the U.S. Supreme Court rejected appeals from the eight inmates, who contended they were entitled to know the source of the drugs in order to avoid unnecessary pain during the executions.

Arkansas uses potassium chloride in combination with vecuronium bromide and midazolam. The latter drug is intended to render the inmate unconscious before the other two chemicals are administered to paralyze the lungs and stop the heart. 

Death penalty opponents contend midazolam is not effective, citing several executions in three other states in which the condemned appeared to writhe in pain before succumbing. 

The lethal injections in Arkansas are set to take place in pairs from April 17 to 27.

No state has executed more than two men in a single month in the past 20 years and none has performed eight executions in 10 days, according to the Washington-based nonprofit Death Penalty Information Center. 

(Editing by Colleen Jenkins and Peter Cooney)