Police were last night breaking up the terror cell which attacked Glasgow airport and attempted to bomb London, carrying out a series of dramatic raids and arrests.

They detained four men and a woman - most, if not all, foreign nationals - but at least one key suspect in the network was reported still to be at large.

The investigation concentrated on the quiet village of Houston. It is a short drive from Glasgow Airport, where terrorists smashed a Jeep Cherokee into the main terminal building on Saturday.

The 27-year-old passenger of the Jeep has been arrested and is being held at the high-security Govan police station, while the driver is critically ill in hospital under armed police guard.

In a series of other raids yesterday, officers detained a 26-year-old man and a 27-year-old woman on the M6 in Cheshire, arrested a 26-year-old man man in Liverpool, and searched a house in Newcastle-under-Lyme in Staffordshire, believed to be the home of the couple held on the M6.

Thousands of travellers faced chaos with around one-third of flights from Glasgow Airport cancelled yesterday. Planes were diverted to Edinburgh, Prestwick and Newcastle. An indication of the extent of global concerns came when two of the world's busiest airports, JFK in the US and Heathrow's terminal 3, were closed briefly yesterday following reports of a suspicious package.

They reopened once police confirmed the items were safe.

In a further twist in Scotland yesterday afternoon, Army bomb disposal officers carried out a controlled explosion at the Royal Alexandra Hospital in Paisley, where the driver of the Jeep used in the attack was taken for treatment to severe burns.

Police sources told The Herald that the car was thought to belong to a doctor who rented the property in Neuk Crescent, Houston, to the two Asian men suspected of attacking the airport and said to have been living there for approximately six weeks. No explosives were found in the vehicle.

As a forensic team searched the Houston property and a van parked nearby, senior police officers asked the public to be vigilant.

They issued an urgent appeal for information about the Jeep Cherokee, registration L808 RDT.

Sources revealed it contained propane gas canisters, similar to those used in the attempted attacks on London. John Malcolm, Strathclyde's assistant chief constable (crime), last night appealed for information about sightings of the 4x4 over recent weeks.

He issued a plea for the public to provide videos or photographs of the incident and its build-up. Mr Malcolm said: "I am delighted to report we have had an excellent response from the public with an average of 100 calls every hour.

"This reflects the outrage felt in our communities at this act and the calls we are receiving are supportive of the police actions. I am satisfied this investigation is progressing dynamically at pace and I have extensive resources dedicated to this inquiry."

Deputy Assistant Commissioner Peter Clarke, Scotland Yard's anti-terror chief, who has a Britain-wide remit, travelled to Glasgow yesterday, emphasising the critical role of the city in the UK-wide operation.

He said: "I am absolutely convinced we will need the support of the public in bringing this investigation to a successful conclusion.

"In terms of the wider investigation, we are learning a great deal about the people who were involved in the attack here in Glasgow and the attempted attacks in central London. The links between the three attacks are becoming ever clearer.

"We are pursuing many lines of inquiry and I am confident, absolutely confident, that in the coming days and weeks we will be able to gain a thorough understanding of the methods used by the terrorists, of the way in which they planned their attacks and of the network to which they belong."

Officers believe at least one of the Mercedes cars used in Friday's attempted terrorist attack on London's West End came via Scotland, as it was logged on the national Automatic Number Plate Recognition system, a network of hi-tech cameras across the country established to counter terrorism.

The revelation has fuelled concerns that there is an Islamic terrorist cell using Scotland as a base.

Kenny MacAskill, the Justice Secretary, confirmed that the perpetrators of the attack on the airport had been here for some time but were not Scots.

He said: "We have evidence to believe that these people did not emanate from Scotland, apart from some evidence of them having resided here for a period of time. They were not born and bred here."

Prime Minister Gordon Brown said Britain's message to the terrorists must be: "We will not yield, we will not be intimidated, and we will not allow anyone to undermine our British way of life."

He said it was "clear" the attacks in London and Glasgow were carried out by people who were associated with al Qaeda.

Home Secretary Jacqui Smith chaired a meeting of the emergency contingencies committee Cobra. She thanked police and emergency services for their "continued hard work" over the last 24 hours and confirmed she would make a statement to MPs in the House of Commons today. First Minister Alex Salmond insisted that Scotland would not be beaten by terrorists. Speaking at Glasgow airport as it re-opened 24 hours after the attack, while the burned-out remains of the car remained, he said: "My job is to get Scotland back on its feet and make sure it doesn't affect in any way the Scottish economy."

Airports and railway stations up and down the country have tightened their security arrangements, and police have stepped up patrols in London. Extra officers will be deployed to the capital's landmarks and main railway stations, as well as Heathrow Airport and London City Airport, Scotland Yard said.

Police in London will also make greater use of their power to stop and search people under the Terrorism Act as a "visible deterrent and disruptive tactic".

Meanwhile, ABC News suggested that the US had prior intelligence indicating Glasgow airport was a possible target for attack.

Michael Chertoff, the US Secretary of Homeland Security, told the American network last night: "I think there was a little bit of a misunderstanding in the ABC report that it suggested that we had taken some specific security measures with respect to flights to Glasgow.

"In fact, what we have done since last August - and we've intensified this in the last few months - is increasingly put our air marshals on flights to various airports in Europe," he said. Pressed further on whether his department had "specific intelligence that Glasgow was a target" he added: "I'm not going to comment on specific intelligence either to say we had something or we didn't have something.

"What I will say is everything that we get is shared virtually instantaneously with our counterparts in Britain and vice versa.

"So you can rest assured that whatever information the US government and intelligence community had was shared very readily with our British counterparts."

The Glasgow attack followed the discovery of two cars loaded with explosives in London's West End on Friday.

The first, a Mercedes packed with a deadly cargo of petrol, gas canisters and nails, was found by paramedics called to the Tiger Tiger nightclub shortly before 2am after a person was taken ill. The ambulance crew spotted fumes inside the car and immediately called police.

Sources suggested one of the first officers on the scene averted disaster by disconnecting a mobile phone in the car which may have been used to trigger the explosion.

The second car, also a Mercedes, was issued with a parking ticket in Cockspur Street, just yards from the first vehicle, at about 2.30am. It was taken to a car pound off Park Lane at around 3.30am.

Workers at the compound were suspicious of the car because it had a strong smell of petrol. But it was not until later when they heard about the news of the first car bomb they contacted authorities.