Al Qaida warned of a terror attack just days before a former British student allegedly attempted to blow up a transatlantic airliner carrying 278 passengers, it was revealed tonight.
Security services on both sides of the Atlantic were under scrutiny as it emerged Umar Farouk Abdulmutallab was able to board the jet with explosives despite warnings of his extremism, including one from his millionaire father.
Airline passengers were facing the prospect of tighter security checks in the coming days after US President Barack Obama ordered a fresh review of screening processes.
Scotland Yard detectives continued to search the 23-year-old's luxury apartment in a central London mansion block as it emerged an al Qaida operative in Yemen threatened the US and said "we are carrying a bomb" in a video posted online four days before the attack.
The student was charged in hospital last night with attempting to destroy the aircraft during its final approach to Detroit airport on Christmas Day, the US Justice Department said.
Abdulmutallab, who studied mechanical engineering at University College London between 2005 and 2008, was also charged with with placing a destructive device on the Northwest Airlines Flight 253.
A fresh British visa request was refused in May after he applied for a bogus course, Whitehall sources said.
As one of his former teachers spoke of his shock today, saying the suspect's nickname was once "The Pope", the university spoke of its "sadness".
Malcolm Grant, a provost at the university, said: "UCL is deeply saddened by these events. This is a university founded on equality and religious tolerance, and strongly committed today to respect for human rights. We are co-operating fully with the authorities in their further investigations."
Abdulmutallab claimed he received training and instructions from al Qaida operatives in Yemen, US law enforcement officials said.
In the December 21 video posted on extremist websites affiliated with al Qaida, a bearded man in head-dress, identified as Mohammed al-Kalwi, says: "We are carrying a bomb to hit the enemies of God.
"O soldiers, you should learn that we do not want to fight you, nor do we have an issue with you. We only have an issue with America and its agents, and beware of standing in the ranks of America."
President Obama called for "a review to ... figure out why an individual with the chemical explosive he had on him could get on a plane in Amsterdam and fly into the United States," White House press secretary Robert Gibbs said on American news channel NBC.
According to reports, the family claim Abdulmutallab was radicalised while attending the British International School in Lome, the capital of Togo.
But Michael Rimmer, a Briton who taught the suspect history at the school, said his impression of Abdulmutallab was positive, claming the youngster chose to give £50 to an orphanage rather than spend it on souvenirs in London.
Mr Rimmer said: "At one stage, his nickname was 'The Pope'. In one way it's totally unsuitable because he's Muslim, but he did have this saintly aura."
According to an affidavit filed in support of the criminal complaint, Abdulmutallab had a device attached to his body when he boarded the aircraft in Amsterdam on Christmas Eve.
As the flight was approaching Detroit Airport, Abdulmutallab was said to have set off the device, which resulted in a fire and what appears to have been an explosion.
A preliminary FBI analysis found that it contained a high explosive known as PETN or pentaerythritol.
FBI agents were also said to have recovered what appeared to be the remnants of the syringe found near Abdulmutallab's seat, which is believed to have been part of the device.
US District Judge Paul Borman read out the charges to Abdulmutallab in a conference room at the medical centre where he is continuing to receive treatment for burns.
According to the affidavit, interviews with the passengers and crew of Flight 253 revealed that before the incident Abdulmutallab went to the aircraft's bathroom for approximately 20 minutes.
When he returned to his seat, he said that he had an upset stomach and pulled a blanket over himself.
Passengers then heard what were described as popping noises similar to firecrackers and some reported seeing Abdulmutallab's trouser leg and the inner wall of the aircraft on fire.
He was then overpowered by passengers and crew who used blankets and fire extinguishers to put out the flames. Abdulmutallab was said to have been "calm and lucid" throughout the incident.
When one flight attendant asked him what he had had in his pocket, and he replied: "explosive device."
On landing, Abdulmutallab was taken to the University of Michigan Medical Centre for treatment to his injuries.
Abdulmutallab - who was said to have been travelling on a valid US visa - initially boarded a KLM flight in Lagos, Nigeria, before transferring to the Northwest Airlines flight at Amsterdam's Schiphol Airport.
Following his arrest he was said to have told US investigators that he had been acting on instructions from al Qaida which instructed him to blow up an airliner over American soil.
Gordon Brown said the Government would take "whatever action was necessary" to protect airline passengers.
Security sources said that both the police and MI5 were diverting extra staff and resources to the investigation as a matter of priority in order to establish the significance of the "London link".
Throughout the weekend in London, police search teams searched the imposing mansion block in Mansfield Road, close to Oxford Street, where Abdulmutallab had been living.
Alhaji Umaru Mutallab, a former minister and chairman of First Bank in Nigeria, confirmed his son Umar had been arrested and US authorities revealed that, in November, the father went to the US embassy in Abuja, Nigeria, to discuss his concerns about his son's religious beliefs.
A US law enforcement source said Abdulmutallab's name surfaced on at least one US intelligence database but not to the extent that he was placed on a watch list or a no-fly list.
Delays were caused at UK airports as security was stepped up for passengers flying to the US.
Beefed-up security measures introduced include extra body and hand luggage searches at the departure gate and a requirement that passengers remain seated for the final hour of flight.