London - Seven terrorism suspects, said to include two medical doctors, were being held in Britain Monday in a fast-moving operation to track down the perpetrators of three attempted car bombings in London and Glasgow at the end of last week. The arrest Monday of two men in Paisley, near Glasgow, brought to seven the number of suspects held by police since two foiled car bombings in London and a dramatic attempt to drive a blazing Jeep into Glasgow airport Saturday.
Police have said that none of the suspects are British, as unconfirmed reports claimed that two of the men are believed to be hospital doctors of Middle East origin.
Britain remains on a "critical" state of terror alert, the highest grade possible, after the attempted attacks, which started off with a Mercedes car filled with petrol, gas and nails, parked outside a busy London nightclub in the early hours of last Friday.
Officers were able to defuse the device after being alerted to a "smouldering car" by members of an ambulance crew which happened to be in the central London area, at Haymarket, at the time.
Hours later, police were able to defuse a second Mercedes car bomb in a vehicle wghich had been parked nearby before being towed to a compound after receiving a ticket for being parked illegally.
On Saturday afternoon, two men drove a blazing Jeep into the main airport terminal building at Glasgow, Scotland, in an attempted attack linked to the events in London a day earlier, police said.
The arrest Monday of two men, aged 28 and 25, in Paisley, near Glasgow, was the result of "intensive police operations" in the town, police said.
Meanwhile, it emerged that police in Scotland appeared to have had prior information of the planned attack on Glasgow airport, in which no one was injured, but one of the attackers suffered serious burns.
Officers had tried to contact an estate agent who let a house to one of the Jeep suspects, only 10 minutes before the attack, reports by the BBC and the Press Association said.
The Let-In estate agent was traced from a mobile phone number found during the search of the vehicles used in the attempted attacks in London, sources said.
But the owner of the letting agency, Daniel Gardiner, was only able to respond to police efforts to contact him two hours later - after the attempted attack had happened.
Gardiner said Monday that his tenant - one of the two men in the Jeep during the dramatic attempt - was a doctor who had been seen wearing a stethoscope.
He believed that his tenant, who rented the house only two months ago, worked at the Royal Alexandra hospital in Paisley, where the driver of the Jeep is being treated for serious burns.
Police Sunday carried out a controlled explosion on a car in the hospital car park which it said was linked to the investigations, and on Monday officers were seen cordoning off doctors' living quarters at the hospital.
There was also speculation Monday that one of the men involved in the Glasgow attempt may have driven one of the Mercedes saloon car bombs to the West End of London.
Police in Scotland said the two men involved in the attempted Jeep attack "came to Scotland a short while ago to seek work."
Police have so far declined to comment on the background and nationality of the suspects, except to say that none was British.
Such a development would turn the media spotlight away from British-born Muslims, who had initially been suspected of being behind the failed attacks, and who are held responsible for the transport suicide bombings in London two years ago, with 52 dead.
It would, however, also mark a departure from so-called "home- grown" terrorism in Britain to a new scenario marked by the "import of car bomb terror tactics" from Iraq and Afghanistan, security sources have said.
Reports said a 26-year-old man arrested Saturday evening on a motorway in Cheshire, north-west England, was a neurologist who had just taken up a job at the North Staffordshire Hospital, in Stoke-on- Trent, in the English Midlands.
His wife, 27, wearing Muslim dress, was also arrested as the couple was stopped in a dramatic motorways hunt, with their two-year- old son travelling with them.
Peter Clarke, the head of Scotland Yard's anti-terrorism unit, has said the results in the fast-moving probe were "changing hourly."
Sources said the police had a "goldmine" of information at their disposal, given that the three vehicles used in the failed attacks remained relatively unscathed, and that ample CCTV footage and DNA material was available.
Britain's new Home Secretary Jacqui Smith insisted Monday that it was "not just luck" that no one was killed or injured in the three failed car bombings in London and Glasgow.
"I don't think it is luck, I think it is members of the public keeping an eye out, I think it is incredibly brave police officers and explosives officers, I think it is intelligence that is looked at very carefully," she told breakfast television.
Asked about reports that US Intelligence had recently warned Britain that Glasgow, in Scotland, could be a target, Smith said she was "not certain."
"One of the things I decided to do in this job is not to talk about things that I'm not certain about," said Smith, who is expected to make a statement in parliament later Monday.
She took over the job of Home Secretary (interior minister) last Thursday.
