Last Saturday a fuel-filled jeep crashed into the entrance of Glasgow Airport's main passenger terminal bursting into flames on impact. While Friday, in central London two Mercedes cars jammed with fuel, gas cylinders, and nails, which were parked in the city failed to explode.
A spokesman for the British traffic police said all cars are being checked in public places, particularly at train stations and airports, and the police are advising the public to leave their vehicles at home and to use public transport where possible.
Earlier reports said four people had been arrested over the attacks: two of them were in the jeep that exploded at Glasgow Airport, and the other two were arrested on the M6 motorway in Cheshire during the night.
After the attacks, Britain raised its terror alert to the highest 'critical' level. In a televised address, British Prime Minister Gordon Brown who took over from Tony Blair last Wednesday urged the nation to be vigilant.