The force has been told it will need to make savings of at least �6m over the next two years, because of the way the government funds police forces.

It warns that 100 police officer posts would have to go unfilled in order to balance the books.

Letters outlining the difficulties have been sent to the county's seven Labour MPs, including the Prime Minister.

Deputy chief constable Jon Stoddart said: "The tragedy of the economic pressures facing us is that we are literally the victim of our own success.

Any loss of police officers will impact on crime levels and detections, reducing the force's ability to protect our communities Anne Wright Chairman, Durham Police Authority

"Over the last decade we have, through over 600 efficiency initiatives, generated more than �12m in savings and budget reductions and we have had, for many years, the lowest council tax precept of the non-metropolitan forces in England and Wales.

"If we are forced to further squeeze finances, cutting the number of front-line officers is a possibility we may not be able to avoid."

A delegation headed by Durham Police Authority chairman Anne Wright and chief constable Paul Garvin visited London to lobby County Durham MPs to fight for more funding.

Mrs Wright said that while the government's capping formula did apply to all police authorities, it unfairly penalised those like Durham which exercised care with their spending.

She said: "Setting the budget this year was extremely difficult and our advisers tell us we will have to make savings of at least �6m over the next two financial years unless there are changes.