text: Umar Farouk Abdulmutallab, 25, pleaded guilty to attempting to blow up a commercial plane as a would-be suicide mission for al-Qaeda.
  His family quickly called on the US government to review the sentence.
  Abdulmutallab was badly burned when a bomb sewn into his underwear failed to detonate fully, prosecutors said.
  Almost 300 people were on the flight from Amsterdam to Detroit.
  Some of the passengers from the flight were in the courtroom as Federal Judge Nancy Edmunds announced the sentence.
  Profile: Umar Farouk Abdulmutallab
  "This was an act of terrorism that cannot be quibbled with," Judge Edmunds said, as she imposed the maximum sentence.
  The son of a Nigerian banker and a former engineering student at University College London, Abdulmutallab faced eight counts against him, including terrorism and attempted murder.
  Al-Qaeda in the Arabian Peninsula (AQAP), a militant group based in Yemen, said it was behind the attempted attack.
  In statement to the BBC, the family of Abdulmutallab said they were "grateful to God that the unfortunate incident of that date did not result in any injury or death".
  "We strongly appeal to the American justice department to review the life sentence," they said. "We also appeal to the Federal Republic of Nigeria to continue with their support and engage with the American government to ensure that a review is made."
  Ahead of the sentencing, assistant defence lawyer Anthony Chambers argued that a life sentence for Abdulmutallab would be unconstitutional, since no other passengers were hurt.
  By Mark LobelBBC News, Lagos
  Many more young Nigerians have been radicalised since Lagos-born Umar Farouk Abdulmutallab's actions linked the West African country to al-Qaeda.
  But the organisation behind their radicalisation is Boko Haram, a local religious group that has turned militant. It wants Nigeria ruled by strict Islamic law and its recruits take quite different journeys from that of the man in his twenties from a very wealthy northern Nigerian family, now in the hands of the US penal system.
  A neighbour of the Abdulmutallab family in Kaduna, prominent rights activist Shehu Sani, told me a lighter sentence would give Umar Farouk a deserved chance to rehabilitate. The blame should lie with the terrorists who took advantage of the model student, as he was too young to know better, he said.
  Some in the Muslim north think the whole case is a US conspiracy. There is far less sympathy for him in the Christian south. Matthew, a banker, said that a death sentence would be justified. Having harmed Nigeria's image, as Boko Haram is doing now, Matthew said the 25-year-old does not deserve a second chance.
  Sentencing guidelines directed the judge to impose a mandatory life sentence, but Mr Chambers appealed for a lighter term.
  "Not one passenger lost his or her life. Not one passenger suffered life-threatening injuries," he said.
  Prosecutors said a life sentence was warranted because an attempted terror attack heightens public fear and burdens airports with expensive and time-consuming security procedures.
  As part of the sentencing hearing, four passengers and a crew member aboard Flight 253 made statements, telling the judge the event had forever changed their lives.
  A video from the FBI showing the power of the explosive material found in Abdulmutallab's underwear was also shown at the hearing. As the video played Abdulmutallab twice said loudly "Allahu akbar" - Arabic for "God is great".
  Abdulmutallab himself made a brief statement. During the short trial, he had fired his lawyer and attempted to represent himself.
  "Mujahideen are proud to kill in the name of God," he said in court. "And that is exactly what God told us to do in the Koran... Today is a day of victory."
  "In quick response to some of the things that have been said, I say my life and the lives of Muslims have also changed due to the attacks on innocent civilians," he added.
  On the second day of his trial, in October, Abdulmutallab unexpectedly declared that he would plead guilty to all charges.
  The bomb was a "blessed weapon to save the lives of innocent Muslims", he told the court.
  "The US should be warned that if they continue to kill and support those who kill innocent Muslims, then the US should await a great calamity... or God will strike them directly," he added.
  Investigators said Abdulmutallab admitted he was working for AQAP, and had been inspired by and had met Anwar al-Awlaki, a radical cleric who was killed in 2011 by a US drone strike in Yemen.
  Abdulmutallab received the bomb, as well as training, from AQAP before travelling from Nigeria to Amsterdam.
  There he boarded Northwest Airlines Flight 253 to Detroit, which was carrying 279 passengers and 11 crew members.
  The bomb was not picked up in security checks at airports in Lagos and Amsterdam.
  On board, the bomb failed to detonate completely and passengers had to put out the fire.
  Abdulmutallab's father, Alhaji Umaru Mutallab, an influential banker who is well connected in Nigerian politics, said he had approached the US embassy officials and Nigerian authorities in 2009 to warn them about his son.
  Abdulmutallab was already on a US watch list, but not a no-fly list.
target: A Nigerian man accused of trying to bomb a US-bound flight on Christmas Day 2009 has been sentenced to life in prison without parole.