A fifth person was arrested yesterday after a fuel-filled jeep was rammed into Scotland's busiest airport, a terrorist attack that police said was linked to two failed car bombings in London.

Three of the arrests were in northern England and followed the detention of two men, who witnesses described as Asians. They were seized on Saturday immediately after they slammed a Jeep Cherokee into Glasgow airport, about 640 km north of London, and set it ablaze.

The attack, which injured five people and damaged the airport entrance, came just 36 hours after two car bombs loaded with fuel, gas canisters and nails were found on the busy streets of central London primed to detonate.

After the series of threats, Britain raised its national security level to "critical", meaning the risk of another attack was imminent, and increased security at airports.

Witnesses in Glasgow said the two men raced their green jeep into the airport terminal's glass doors before dousing it in petrol and torching it.

Following the threats, British Prime Minister Gordon Brown convened a meeting of his top security chiefs to discuss ways to handle the first big test of his leadership.

"Irrespective of Iraq, irrespective of Afghanistan, irrespective of what is happening in different parts of the world, we have an international organization trying to inflict the maximum damage on civilian life in pursuit of a terrorist cause that is totally unacceptable to most people," he told BBC television.

"Terrorism can never be justified as an act of faith. It is an act of evil in all circumstances," he said.

British Muslim groups have condemned the incidents and urged their fellow brethren to cooperate with the authorities.

"We are utterly appalled by this sinister plot and commend the professionalism of the security services in aborting it," the British Muslim Initiative said in a statement.

Though police linked the attack to the thwarted London car bombings, they did not say how. The failed London plot bears the hallmarks of a previous Al-Qaida plan to attack the British capital with fuel-filled cars, and another militant plan to bomb a major nightclub, they said.

"There are clearly similarities and we can confirm that this is being treated as a terrorist incident," the Glasgow area's top police officer Willie Rae said.

The airport attack and the failed bombings come almost two years after the July 7, 2005, attacks on London's transport system, in which four British Muslims blew themselves up killing 52 commuters.

"We are dealing with a long-term threat. It's not going to go away in the next few weeks or months," Brown, himself a Scot, said in a somber appraisal of the terrorist threat facing Britain.

In a town a short drive from the airport in Glasgow, Scotland's biggest city, police in white body suits searched houses and set up forensic tents behind one building.

Neighbors said two Asian men had moved into one of the houses a month ago but had kept very much to themselves.

"I don't remember seeing them at all," said Mae Gordon, 67. "They were the only people around here you would never see."

Police said the three arrests in northern England were related both to the Glasgow and the London attacks, but did not provide further details. Two of the men were arrested overnight on a major highway and the third later yesterday. One of the two men detained at Glasgow airport was badly burnt and listed in critical condition in a hospital.

Britain has seen an increase in terrorism-related attacks since the September 11 strikes on the United States and since it joined US forces in invading Iraq in 2003. Some analysts said the failed car bombings in London and the attack on Glasgow airport might be designed to exert pressure on Britain to withdraw its troops from Iraq and Afghanistan.

(China Daily via agencies July 2, 2007)