Ohio is to try again to execute a man convicted of murder after his death by lethal injection was botched earlier this week when technicians spent two hours in a futile hunt for a vein able to take a needle.

At one point, Romell Broom, who was convicted of rape and murder of a teenage girl 25 years ago, tried to help prison officers find a suitable vein by moving around and flexing his muscles. The prison governor later thanked him for his cooperation.

What critics of the death penalty are describing as the "virtually unprecedented" failure of the attempt to execute Broom, 53, has again raised questions over its continued use in the US. Concerns have also been raised over a case in Texas in which a man is facing execution despite an admission by the judge and prosecutor in his trial that they were lovers.

Prison officers described how, after about an hour of hunting for a suitable vein, Broom helped them by turning on to his side, by moving rubber tubing along his arm and by flexing his hand and muscles. At one point, technicians found what appeared to be a suitable vein but it collapsed as they inserted a needle, apparently because of past drug use.

Broom, who was convicted of kidnapping, raping and killing 14-year-old Tryna Middleton, became so distressed that he lay on his back and covered his face with both hands. One of the execution team handed him a toilet roll to wipe away tears.

The prison director, Terry Collins, contacted Ohio's governor, Ted Strickland, to tell him of the difficulties. The governor issued a temporary reprieve.

Collins later thanked the condemned man for what he said was the respect he showed toward the execution team and for the way he endured the ordeal.

One of Broom's lawyers, Adele Shank, who witnessed the failed execution, said her client was clearly in pain.

"It was obviously a flawed process," she said. "He survived this execution attempt, and they really can't do it again. It was cruel and unusual punishment."

Broom's legal team has now asked Ohio's supreme court to cancel the execution but state officials today said they will attempt it again next week.

The Death Penalty Information Centre in Washington said that the botched attempt is the first of its kind since the electric chair failed to kill a murderer, Willie Francis, in Louisiana in 1946. Francis argued that a second attempt to execute him would be unconstitutional but the supreme court ruled otherwise and he was electrocuted the following year.

"This is virtually unprecedented," said the DPIC's director, Richard Dieter, said of the Broom case. "The public in the US are increasingly jaded about the death penalty. There is evidence of innocent people executed, prosecutors sleeping with judges and being ignored, failed executions. At some point enough is going to be enough and even people who support the death penalty are going to let it go".

There are fresh questions about the legal process around the death penalty in Texas, which carries out by far the largest number of executions in the US. The state's court of criminal appeals has turned down an appeal from a man on the brink of execution who said there were questions over the fairness of his trial after it was revealed that the judge and prosecutor kept secret that they were lovers. Charles Hood was convicted of the 1989 robbery and murder of two people.

The appeals court said that the defence should have raised the issue of the affair at the original appeal. But defence lawyers said that it was no more than a rumour at the time and was only confirmed by another official in the prosecutor's office hours before Hood was originally to have been executed last year. The two people involved later confirmed their affair.

One of Hood's lawyers, David Dow, called the decision "gutless" and the American Bar Association ethics committee described it as a "blot on the Texas judiciary".

Texas is also grappling with revelations that it may have executed an innocent man five years ago after he was convicted of murdering his three children through arson on the basis of deeply flawed "scientific" evidence that has been compared to the stuff of witch trials.