The BBC's Stephen Sackur on reactions to the sentence

He was convicted last year for conspiracy to bomb the main federal building in Oklahoma City. The bombing was the worst ever incident of terrorism in the US, and killed 168 people.

Nichols, 43, was also found guilty on a second charge of involuntary manslaughter, relating to the deaths of eight federal agents who died in the explosion.

At his trial, which ended in December, the jury had been unable to agree on the severity of his punishment, leaving the decision to the judge.

In 1995 Nichols had helped his old army colleague, Timothy McVeigh, build the truck bomb which destroyed the Alfred P Murrah building in the worst act of terrorism in American history.

Terry Nichols refused to supply further information about the bombing

The life sentence without parole is the maximum possible sentence for the conviction that Nichols received, and was welcomed by relatives of those who died.

Judge Richard Matsch described Nichols as "an enemy of the Constitution".

The mother of one of the Oklahoma bomb victims describes her reaction to the sentencing

There were hints in court that Nichols might receive a lighter sentence in return for providing information about the bombing, particularly about a third suspected conspirator whom several witnesses claimed to have seen.

But Nichols declined to reveal anything about the planning of the attack or about those involved.

After hearing emotional testimony from relatives of victims on how their lives had changed forever, Judge Matsch said the former farmhand should remain in prison for the rest of his life.

Angela Richerson, whose mother died in the bombing, celebrates the sentence

There still is a widespread belief, especially among the families of those who were killed by the bomb, that people other than Nichols and McVeigh were involved in the bombing.

But according to BBC correspondent Stephen Sackur, the police have followed up all the available evidence that might have led to other convictions. After Nichols's silence today, it seems unlikely that he will reveal any more.

Nichols still faces a further charge of murder brought by the Oklahoma state authorities, which carries a possible death penalty.