The U.S. Supreme Court Tuesday, allowed Arizona to proceed with the execution of a convicted murderer after the inmate's demand that  the state reveal the lethal drugs to be administered was rejected.

Joseph Wood, 55, was given the death sentence for the 1989 killing of his 29-year-old ex-girlfriend and her 55-year-old father Gene.

Wood is one of six death row inmates who sued Arizona last month over the secrecy shrouded over the lethal injections and said that his First Amendment rights were violated.

The 9th U.S. Circuit Court of Appeals granted a stay on his execution Saturday saying that Wood could suffer "irreparable harm" unless the state disclosed information about the drugs and the qualifications of the medical staff conducting the execution, reports Reuters.

The decision is the first time an appeals court has allowed a stay on an execution based on the subject of drugs secrecy, said Richard Dieter, director of the Death Penalty Information Center in Washington, D.C., according to the Associated Press.

However, the U.S. Supreme Court cleared the way for Arizona to carry out the execution that was set for 10 a.m. (1 p.m. EDT) in the state prison in Florence.

The botched execution of Clayton Lockett in Oklahoma state prison prompted the death row inmates to challenge their sentences seeking proper knowledge about the lethal drugs used. Lockett was administered a combination of three untested drugs following which he suffered pain for 45 minutes and died of heart attack.

In  June, 21 death row inmates of Oklahoma filed a lawsuit against prison officials to prevent them from using "untested and unsound" execution methods.

The lawsuit alleged that the measures used by the state "create a substantial risk of severe pain, needless suffering and a lingering death."

According to Death Penalty Information Center, 25 inmates have been executed this year.