Airports face multi- million pound bills for their growing security costs, under Government plans to ease the burden on the police.

Legislation being drawn up will transfer responsibility for threat and risk analysis at airports, and for paying the bill, from the local police force to the airport owner.

Airport operators are angry at the proposals, warning the extra cost would be a heavy blow; but it would give police extra cash towards the fight against crime.

The cost of policing regional airports is usually kept under wraps for security reasons, but is likely to run into millions and is on the rise because of the heightened terror threat.

Edinburgh Airport recently set up a police unit with 44 officers at an annual cost of £2.5 million, while the security bill for the small City of London airport is £7m a year.

The proposals come as airports wrestle with a double whammy of soaring fuel prices and plans for a new tax on every plane journey.

Last summer's failed bomb attack at Glasgow Airport alerted security experts to the fact regional airports, as well as Heathrow and Gatwick, were potential terror targets.

At the moment only nine airports are designated to pay for their own policing, including the three main London airports, Manchester and Birmingham, but not Bristol International, or Exeter.

Now Transport Secretary Ruth Kelly has decided the two-tier system is unfair because of the astonishing growth of regional airports and is determined to create a level playing field.

Bristol is a successful regional airport already, with passenger numbers up 10.78 per cent to 3,641,562 so far this year, and aircraft movements up 3.12 per cent to 46,466.

And there is an ambitious masterplan to expand much further, increasing the airport's capacity to nine million passengers a year by 2015, and 12.5 million by 2030.

It is unfair taxpayers are subsidising profit-making private enterprises as long as the local police force is meeting the bill, Ms Kelly believes.

A consultation paper notes football clubs and shopping centres are already charged for policing, as are mainline rail stations and the Channel Tunnel.

Under the proposals, part of a Transport Security Bill and due to come into force in 2010, airport operators would pay to "protect the airport, the people who work there and passengers from the threat of crime, including terrorist activity". They would also be required to produce an airport security plan that clarifies roles and responsibilities and ensures that actions are taken to mitigate threats where the risk is unacceptably high.

The document concludes: "The current police funding arrangements at those UK airports that are not designated are no longer fit for purpose.

"This situation does not reflect the evolving range of threats and the increasing size and complexity of airports over the years. Indeed, some non-designated airports are now larger in scale than some of those that are designated.

"This two-tier approach to airport policing sees some airports having to go through a process of analysis of what the police role is at an airport, and meeting the associated costs, while others do not.

"This is discriminatory and needs to be replaced."

Ministers have accepted that policing costs should generally be met by the airport sector and note: "Clearly the financial impact for airport operators that are meeting such policing costs for the first time, could be significant."

Gloucestershire Airport, which has about 20,000 passengers a year and flies to Belfast, Jersey and the Isle of Man, believes it will be not be affected as it is too small.

A Department for Transport spokesman said the consultation ended on October 8, adding: "The nature of air travel has changed and so has the threat."

A spokesman for Avon and Somerset Police, which cover Bristol International, said they would not want to comment during the consultation period.

A spokesman for Bristol International Airport said: "We are currently studying the document and will be putting together a response in due course as part of the consultation process."

Neil Pakey of Peel Holding, which owns Durham Tees Valley airport, said: "The assumption that all airports are profitable is incorrect and we have longstanding commercial agreements with airline operators that don't allow us to pass the costs on."