In a report commissioned by Tory leader David Cameron, ex-Metropolitan Police Commissioner Lord Stevens of Kirkwhelpington will say that ministers lack a clear border strategy.

According to advance extracts released by the Conservatives, it will point to last summer's attempted car bomb attack on Glasgow Airport - where no armed police were on duty - as evidence of the inadequate security coverage.

Among the weaknesses it will point to are the air cargo system - which, it says, is vulnerable to plots to place explosives aboard aircraft - and the plethora of small airfields within easy flying distance of continental Europe.

"The lack of a clear border security strategy has resulted in a situation in which agencies are unaware of where their shared priorities lie," the report will say.

"This has resulted in key duties not being carried out, resources not properly allocated, organisations not working together as they should and focus being placed on narrow border control issues, specific to each agency and not the overall border security picture of the UK."

Mr Cameron will formally launch the report with Lord Stevens - whom he appointed to advise him on border security - and shadow home secretary Dominic Grieve.

The Tories will hope that its publication will embarrass Prime Minister Gordon Brown who has also co-opted the former Met commissioner to advise him on counter-terrorism issues.

The Conservatives are committed to establishing a dedicated border police force with its own chief constable reporting directly to the Home Secretary.

Earlier this year, the Government announced the formation of the new UK Border Agency which brought together officers from the Immigration Service, Revenue & Customs and UK visas in a single service. However, the Tories say that the changes do not go far enough.