A police officer stands guard outside Scotland Yard, central London Sunday, July 1, 2007

British police have arrested five people in connection with an attempted car bombing at Glasgow airport in Scotland on Saturday.  The security alert level throughout Britain is at its highest stage and the search continues for other suspects involved in the Glasgow attack and two attempted car bombings early Friday in central London.  VOA's Sonja Pace has details from the British capital.

Police confirmed the arrests on Sunday and said a search is underway for other suspects.  Police were searching several houses near Glasgow airport and stepped up security around other airports and public places.

Home Secretary Jacqui Smith called for continued vigilance.

"With the threat level raised to critical it is obviously very important that people remain vigilant and they carry on reporting suspicious events to the police," Smith said.

There have been three attempted car bombings in two days.  On Saturday two men tried to ram their four-wheel drive vehicle through the entry way of the terminal building at Glasgow airport.  The car burst into flames and the occupants got out, were subdued by police and passersby, and arrested. 

One of the men in the car sustained severe burns and remains in critical condition in a local hospital.

Police officers stand guard behind a raised vehicle barrier outside Buckingham Palace, Central London Saturday

 Early Friday, two explosive laden cars were found in central London.  One had been abandoned near a nightclub in the city's popular Haymarket district; another was left in an underground parking garage and towed to an impound lot, where police later discovered gas canisters, gasoline and nails inside.

British authorities and terrorism experts say all indications are this is the work of Muslim extremists linked to or inspired by al Qaida.

Prime Minister Gordon Brown has been meeting with members of his cabinet, security and police officials.

"The police have made it clear that they regard these as similar investigations and that there are features in what has happened in both Glasgow and London that lead them to mounting one set of investigations into this incident," Mr. Brown said.

It has been a rough beginning for Mr. Brown who took over as Britain's prime minister last Wednesday.  He urged continued vigilance and also understanding for delays and inconveniences that will be caused by the security operations.

"In my view the terrorist threat is long term and it is sustained," Mr. Brown said.  "It is about those people who are essentially violent extremists, who have a grievance against society, particularly against the values that we represent and the values that decent people in all religions represent.  And it is their intention to inflict the maximum of damage in any parts of the world to make their propaganda point."

Mr. Brown also said it is important for people to go about their daily business to send a message to the terrorists that they will not be cowed by these acts.