Amnesty International brought the men together in New York before a hearing of the human rights committee of the UN tomorrow that will call for a moratorium on executions around the world as a first step towards abolishing the death penalty. It is the ultimate argument, the campaign believes - the testimony of individuals who managed to survive the system, but who came close to being killed despite their innocence.

Venezuela became the first country to remove the death penalty in 1853, and the abolition movement has grown, with 133 states members. Britain abolished the penalty in 1967. As countries drop away, attention focuses on the remaining practitioners.

Last year at least 1,591 people were put to death in 25 nations, but 91% of those were executed in six countries: China, Iran, Pakistan, Iraq, Sudan and the US. China is known to have executed more than 1,000 prisoners in 2006, but the real figure may be closer to 8,000. Twelve US states put a total of 53 people to death last year, but the practice has fallen to its lowest level in a decade after the supreme court decided to hear arguments about the humanity of the lethal injection method.

The UN resolution, backed by 72 countries including the 27-nation EU, has no power to enforce a moratorium, but it is seen by campaigners as a chance to apply pressure for reform on those countries teetering on abolition.

Amnesty's death row expert, Piers Bannister, said the men's stories "provide graphic evidence that the death penalty is administered by flawed systems that put innocent people at risk".

Edward Edmary Mpagi

Mpagi spent 18 years on death row in Uganda. The hardest moments were when fellow inmates were taken away from their cells, leaving him to wonder if it would be his turn next. He counted 52 men who were taken for execution, often in batches of 10 or 11 at a time. The first thing prisoners would know would be a feeling in the air, what Mpagi calls "something fishy". Then the prison guards would take an inmate away. The other prisoners would shout "So-and-so is going!" and the condemned man would cry: "I am going! I am going to meet my Lord!" Then there would be a three-day period while the condemned men were allowed to prepare themselves for death and take their last rites from a priest. Mpagi would hear the men singing to keep up their spirits.

At the end of the three days, he would hear them being led to the execution chamber, and then the thud of the body as it fell from the gallows.

Finally, the sound of nails being knocked into coffins. Only then, when all the men had been hanged, would he be able to relax. "You think, 'It could be me. Maybe this time I am going'. Only when the exercise is over does your heart come back. Until then, there is great fear."

He was arrested, aged 27, in 1981 and sentenced to death the next year for the murder of a neighbour in Masaka. Mpagi thought he saw the dead man, George William Wandyaka, standing at the back of the court during the trial.

A few years later, further sightings were made of the man in Jinja, in eastern Uganda. It transpired that Wandyaka's parents had carried a grudge against Mpagi's parents, and had staged the murder to hurt them.

In 1989, the authorities in Masaka confirmed that Wandyaka was alive, and informed the attorney general, though Mpagi remained on death row for a further 11 years. Since coming off death row he has dedicated himself to campaigning against executions. A devout Christian, he says he has forgiven all those involved with what happened to him, even Wandyaka who died in 2002 before Mpagi had the chance to meet him.

Ray Krone

In 2002 Ray Krone became the 100th death row prisoner to be freed in the US. He was your model citizen at the time of his arrest on New Year's Eve, 1991, aged 35. He had served in the US Air Force for six years and had a spotless criminal record. "I was the kind of guy who, if you had broken down in your car in the middle of the night, you could call up and I would come."

Then it all went wrong. A barmaid was stabbed to death in the CBS Lounge where he used to drink near his home in Phoenix, Arizona. Someone said that he had been having a relationship with the woman, which was not true, and a medical examiner matched his teeth to a bite mark found on the victim's arm. He was put on death row after a trial lasting barely three days.

For the first few months he was in despair. "You keep thinking, 'Why me'?, beating yourself up, you think you can't live through this."

But over time he came to realise that if he was to fight the system he had to understand how it worked. He managed to get hold of legal books and study, and he kept pressing his case with the prison authorities. In 2001 the state of Arizona made it easier for prisoners to gain access to DNA testing, and when the victim's clothing was analysed, police databases threw up the name of a convicted sex offender who had been on parole at the time of the murder and staying at his mother's house next to the CBS Lounge. Krone was released the following year.

Before his arrest he supported the death penalty. "I saw it as the end of the line, the just deserts for those who commit heinous crimes," he says. Now he campaigns against it. "If they can do it to me, they can do it to anybody."

Sakae Menda

Thirty-four years after he was sentenced to death for the murder of two people in Kumamoto, the southern Japanese island, Sakae Menda became the first prisoner on death row to be exonerated. The authorities had the evidence they needed to prove that he was innocent, including a firm alibi and a statement from a witness saying that she had lied under duress, but he had to wait decades for them to act on it. "Japanese law is very arbitrary," Menda says.

He was 22 in 1949 when his world caved in. He was staying at a motel that he discovered to be a brothel and got talking to a working girl who told him that her mother and a corrupt police officer had forced her into prostitution at the illegally young age of 16. When the officer found out, he decided to remove Menda as a potential threat by having the unrelated murder of two people pinned on him. He forced a confession out of him.

Menda expected to be executed within six months. Under the Japanese system, death row inmates, unless they are involved in legal appeals, can be taken away for execution at any time, with little notice. He was ready to give up hope, until a Catholic priest encouraged him to seek a retrial. "It's harder to live than to die," the priest told him. From that day he never felt like giving up again. "Whenever I saw inmates being taken away for execution - and there were about 35 of them during my time on death row - I would feel even stronger in my fight for my freedom."

That freedom came in 1983. Japan's death row remains in place and Menda continues to campaign against it. "So long as people stand in judgment over others, mistakes will be made and innocent men will die," he says.