CONDEMNED Oklahoma bomber Timothy McVeigh has spent his last night in a cell before being executed by lethal injection.

The biggest mass murderer in US history will die at 1pm British time today - barring a last-minute stay of execution.

McVeigh detonated a huge truck bomb outside the Alfred P Murrah federal government building in Oklahoma City, on April 19 1995, killing 168 people, 19 of them children in a daycare centre.

To pay for the attack, McVeigh will be strapped to a table and given the injection.

The 33-year-old will be the first person to be put to death by the federal government since 1963.

Today, shackled by his arms and legs, he will be led to the execution chamber, a green-tiled room in the middle of a windowless, one-storey building in Terre Haute, Indiana.

There he will be strapped to the T-shaped, padded table and have a tube inserted into his arm to deliver the lethal chemicals. A curtain will be drawn back to reveal the officials and 25 witnesses who will watch his final minutes.

The witnesses will comprise ten members of the US media, ten relatives of his victims, sat behind tinted glass, and five chosen by McVeigh himself.

No members of his family will be there, but novelist Gore Vidal will attend at McVeigh's invitation.

The Gulf War veteran will be given the chance to say his final words and a special telephone will be used to check for any last-minute stays of execution.

His last words will confirm the image he has created, that he is in control and knows he will not be forgotten in America for a very long time, when he quotes an excerpt from William Ernest Henley's 19th century poem Invictus.

"I am the master of my fate. I am the captain of my soul," he will say.