LONDON – Two Muslim extremists who butchered a young British soldier on a busy London street in full view of stunned passersby were sentenced Wednesday to long prison terms, including life without parole for the leader of the attack.

A judge harshly denounced the men for planning and carrying out a frenzied public “bloodbath” for maximum effect, saying that Michael Adebolajo and Michael Adebowale’s “sickening and pitiful conduct” warranted severe punishment.

Adebolajo, 29, is to spend the rest of his life behind bars. Adebowale, 22, was given a life sentence with the possibility of parole, but he cannot apply for early release before serving a minimum of 45 years.

Their horrific assault in May on 25-year-old Lee Rigby in southeast London was the first fatal Islamic terrorist incident in Britain since suicide bombers aboard London’s transport system killed 52 people in 2005.

The two men were not present in the courtroom when Justice Nigel Sweeney handed down their sentences, having been hustled out after disrupting proceedings by shouting and engaging in a brief scuffle with bailiffs.

The pair were convicted of murder in December. Although sentencing normally takes place soon after a verdict is returned, it was postponed in this case until an appeals court could rule on the legality in Britain of locking up criminals for life without possibility of parole. A decision handed down last week affirmed the applicability of unmitigated penalties for especially heinous crimes.

Sue Hemming of the Crown Prosecution Service, who specializes in terrorist cases, called Rigby’s killing “one of the most appalling terrorist murders” she had ever encountered.

Adebolajo was caught on videotape after the attack holding up a bloody cleaver that he had used to try to decapitate Rigby, a gunner and drummer with the Royal Regiment of Fusiliers. Looking into a bystander’s camera, he described the soldier’s death as “an eye for an eye, a tooth for a tooth” – justified retribution for British participation in the wars in Iraq and Afghanistan – and shouted at bystanders: “You people will never be safe!”

The savagery of the assault, and Adebolajo’s widely broadcast rantings, stoked fears of copycat attacks by “lone wolves” inspired by radical Islam but unaffiliated with known extremist groups or terror cells. Prime Minister David Cameron launched a task force to study whether universities, Muslim charitable organizations, prisons and the Internet had become a “conveyor belt” of Islamist radicalization.

During questioning by police and in courtroom testimony, the two defendants called themselves soldiers of God and referred to members of Al Qaeda as their brothers, though authorities do not believe that the pair was involved with the group.

Adebolajo and Adebowale are British citizens of Nigerian descent who converted to Islam from Christianity. In 2010, Adebolajo was arrested in Kenya with several other men on suspicion of being part of a terrorist plot; he was released and sent back to Britain, where authorities reportedly tried unsuccessfully to turn him into an informer.

On May 22, the pair lay in wait near a barracks in Woolwich, a southeast London neighborhood, to ambush the first soldier they saw. Rigby, shouldering a military backpack and wearing a sweatshirt with the name of a veterans’ charity, was just returning to the barracks from a shift at the Tower of London.

The attackers drove their car straight into him and knocked him to the ground. As he lay motionless, Adebolajo started hacking at his neck and body with the knife. Adebowale soon joined in. Together, they dragged the soldier's body into the middle of the street for public display.

When police arrived a few minutes later, the two assailants brandished the blood-stained cleaver and at least one gun. The men testified later that they wanted to be killed by police in order to become martyrs. Officers shot both men, disabling but not mortally wounding them and taking them into custody.

Before their sentences were pronounced Wednesday, statements from Rigby’s family were read out in court recounting the horror and grief they experienced after the young soldier’s gruesome, premature demise. His widow said their son would grow up without knowing his father and with grisly images of Rigby’s death in the public record.

“We feel that no other sentence would have been acceptable, and we would like to thank the judge and the court for handing down what we believe to be the right prison terms,” the family said after the sentencing through their police liaison, Detective Inspector Pete Sparks. “We feel satisfied that justice has been served for Lee.”

Outside the courthouse, a noisy crowd of protesters from the anti-Muslim far-right English Defense League demanded that Adebolajo and Adebowale be put to death. Britain permanently abolished capital punishment in 1969.

henry.chu@latimes.com

Twitter: @HenryHChu