In other developments in the case Wednesday, a British priest who works in Baghdad said he was warned more than two months ago of attacks on Britain and the United States by a man believed linked to al-Qaeda who also hinted that doctors might be involved.All of the suspects in last week's attempted car bombings in London and a fiery vehicle attack in Glasgow are doctors or other medical personnel. Authorities say the failed bombings bear all the characteristics of an al-Qaeda operation.

Two Middle East doctors who drove a blazing car into Glasgow airport's main terminal left a suicide note to explain the attack, media reports said.

Bilal Abdulla, an Iraqi, and fellow doctor Khalim Ahmed drove the car into the side of the main terminal of Glasgow airport on Saturday. Ahmed is in critical condition in hospital after suffering severe burns.

The Times newspaper and other media said the pair had written an apparent suicide note explaining their motives. It indicated that they had planned to blow up the vehicle at the airport, the Times said.

Police refused to comment on the reports.

Britain reduced its terrorism threat level to "severe," meaning further attacks are still considered likely but not imminent, as was feared when authorities raised the level to "critical" after the failed attacks.

Still, Britain's home secretary asked the public to remain vigilant, saying there was still a "serious and real threat against the United Kingdom."