The UK needs a single border police force to stop terrorists infiltrating through small airfields and remote coastline, a government adviser warns.

Lord Carlile, currently preparing an independent report on anti-terrorist measures for Home Secretary David Blunkett, has described airfields and ports as the "soft underbelly" of the UK's war on terror.

The Lib Dem peer said efforts to stop terrorists bringing explosives or other weapons into the country would be better helped by a having a single force of police officers tackling border security, led by a single chief constable.

He told BBC One's Breakfast with Frost programme that the current arrangements with hundreds of officers spread over a number of forces was not the most efficient way to defend the UK.

Lord Carlile wants a simpler structure

"What I have suggested is that Mr Blunkett might look at the question of whether borders policing might be more effective if there was more central control by a chief constable responsible for all those officers, or something like a single ports and borders police force."

Domestic security

There has been considerable speculation in recent weeks about the level of preparedness in the UK for a major terrorist attack on the scale of the Bali bomb.

The Tories have floated the idea of new Cabinet minister to deal with domestic security, but not along the lines of the US "Homelands" security chief Tom Ridge.

Lord Carlile QC's report said: "The risk of lethal material entering the UK on a light aircraft landing at a busy general aviation airport or remote rural airstrip is real."

Also critical of checks on pilots and air crew, the peer said the public also had an important role to play.

"In the end it is a matter for the vigilance of the public. Private pilots who have a great deal of knowledge, farmers who may have airstrips and all of us to be very vigilant about suspicious activity."

The proposals come as the government confirms it is considering placing "sky marshals" on planes to prevent terrorists hijacking them.

Home Secretary David Blunkett and Transport Secretary Alistair Darling are considering the plans, which would see undercover armed police onboard flights.