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LONDON - The British government has lowered the terrorism threat level from the highest category and sources close to the investigation of last week's bomb plot said police believe they have caught the main suspects.
Home Secretary Jacqui Smith said the decision to reduce the threat level to "severe" from "critical" meant there was no longer "intelligence to suggest an attack is expected imminently", although a "serious and real" threat remains.
The threat level had been raised four days ago when two men rammed a fuel-laden jeep into an airport in Scotland and set off a fireball, a strike linked to two car bombs targeting a crowded nightclub in London that police defused.
Security sources say all of the eight people arrested, including one in Australia, are doctors or have medical links. Prime Minister Gordon Brown ordered a review of recruitment to the health service.
"I have asked ... the new terrorism minister to conduct an immediate review as to what arrangements we must make in relation to recruitment to the NHS (National Health Service)," Brown told parliament on Wednesday.
While no evidence has emerged that medical expertise was central to the plot, the involvement of doctors has caused disquiet in Britain, where nearly 40 per cent of registered doctors are foreign-trained.
Security analysts said the idea that militant Islamists could be working in hospitals, with potential access to dangerous biological or radiological substances, was alarming, even if no such materials were involved in this case.
"If all of these doctors are involved in this cell, that is very disturbing. That is a new dimension entirely for the security services," said M.J. Gohel of the Asia-Pacific Foundation in London.
A British Anglican cleric in Baghdad said he had received a veiled warning from an al Qaeda leader while in Amman in April that attacks were planned against Britain and America and that "the people who cure you will kill you" -- with hindsight, a possible reference to doctors.
Canon Andrew White told the Times he passed the warning, but not the actual words, to a Foreign Office official.
A police source said detectives believed they had now arrested the main potential attackers in a plot that Brown -- in office for only one week -- has said may be linked to al Qaeda.
Two of the suspects are Indians and the rest are from the Middle East. A security source said data on some of them appears in the MI5 intelligence agency's databases on radical Islamists.
Police said a British counter-terrorism officer was en route to Australia to help detectives there question an Indian doctor detained on Tuesday while about to fly out of the country.
Detectives were questioning six people held in London. A seventh man arrested in Scotland after Saturday's attack on Glasgow airport remains ill in hospital with severe burns.
A security source said it was reassuring that some information on the suspects was already held on MI5 databases and that those arrested were not complete unknowns.
"We were far more anxious that we would not have heard of them. That would have been very worrying -- it would have meant our coverage was not necessarily directed in the right places."
Britain has seen a marked increase in terrorism-related plots since the September 11, 2001 strikes on the United States and its decision to join US forces in invading Iraq in 2003.
Four young British Muslims killed 52 people in London suicide bombings in 2005.
- REUTERS
