Armed police are likely to become a familiar sight at both airports and railway stations in the UK for some time, a security expert said yesterday.

Chris Yates, aviation security analyst for Jane's Airport Review, also said restrictions on driving near airport terminals would probably remain in place.

Glasgow Airport reopened yesterday with an increased police presence and strict security measures in place.

Before the attack on Saturday, private cars were already barred from accessing the lanes closest to the terminal building and passengers faced tough security checks on baggage before being allowed to board flights. Only black cabs and airport registered taxis were allowed to stop outside the terminal building.

Yesterday, no vehicles were allowed along the road in front of the terminal. Passengers were being re-routed on foot through the car parks and to a side entrance to the airport building via a covered walkway.

A spokesman for BAA Scotland said: "Partly because this is a live crime scene and as a precaution, we have closed off the forecourt area."

Mr Yates said: "I think what we're talking about here is extra policing, primarily additional policing of all major airports and the critical national transport infrastructure.

"It won't just be airports, at mainline train stations and so on there will be a very visible and probably armed police presence for the time being.

"It's possible restrictions will remain in place on public vehicles, that is your car and my car being allowed to drive up close and personal to the terminal building. We won't be able to drop off or loiter."

Russ Timpson, a chartered fire engineer who designs strategies for airports, said sprinkler systems should be installed more widely in public buildings.

He said: "Sprinkler systems are extremely effective in large, rapid fires."

A BAA spokesman said: "A number of measures have been taken in consultation with various branches of the security services to make the landside part of airports safer."