British police arrested two people in northern England in connection with the attempted attacks in London and Glasgow, police said Sunday.
The two suspects were arrested in the county of Cheshire by counter-terrorism officers, London's Metropolitan Police said in a statement.
"Police have this evening arrested two people in connection with events in London and Scotland on the 29th and 30th of June," said the statement, without giving details.
A burning Jeep Cherokee crashed into the main terminal building at Glasgow Airport on Saturday afternoon. Two people in the car, including one suffering severe burns, were arrested and the airport was evacuated and closed following the incident.
Shortly after the incident, which police described as a terrorist attack, vehicle access was closed at New Castle and Edinburgh airports on a heightened state of alert, while armed police closed off Blackpool airport at the west coast of Britain.
On Friday, police foiled a car bomb plot in central London after they discovered explosives packed into a car outside a nightclub near Piccadilly Circus and another car parked nearby.
Senior police officers said the attack at Glasgow airport was linked to the incident in London, adding that all three vehicles had carried large amounts of flammable materials.
British Prime Minister Gordon Brown urged the public on Saturday night to remain vigilant and support the police after the national security alert level was raised to "critical."
He reassured people that it is right to raise the security level at airports and crowded places.
"The British people must remain united, resolute and strong," he said after chairing a meeting with security officers.
The highest security alert level means imminent attack is expected.
Britain's Home Office has also ordered security to be tightened across the country.