THE bitter battle over plans for a single North-East police force was heading for the High Court last night after the Home Office announced it was pressing ahead with the merger.

Home Secretary Charles Clarke published a fresh study that concluded the amalgamation of the Durham, Cleveland and Northumbria forces was the "only acceptable option".

Chief constables and police authority leaders who met Mr Clarke at Westminster were urged to accept the merger and given a deadline of February 24 to confirm they were willing to merge voluntarily.

But Cleveland said its fight to stop a "super-force" was not over and again threatened a judicial review of a decision it branded expensive, unpopular and irrelevant to fighting crime.

Councillor Dave McLuckie, the police authority's chairman, said: "We would be doing a terrible disservice to our local communities - and our officers and staff - to accept Charles Clarke's invitation.

"What's beyond belief is that he is seeking to force authorities and forces down the merger route when he admits he has no idea about costs, or how huge super-forces could be organised and made accountable."

But the announcement was warmly welcomed by the Durham and Northumbria forces, which said a single strategic force had always been the only option that made sense.

Durham Chief Constable Jon Stoddart said: "It is the best way to safeguard and improve our excellent community policing and, at the same time, tackle extremists, terrorists and the Mr Bigs of serious and organised crime."

Nevertheless, Cleveland's continued opposition ensures the Home Office will fail in its timetable to complete the merger by the middle of next year.

The Home Secretary will instead be forced to trigger a further four-month consultation period and bring an order before Parliament to force the merger through.

It means the final decision would then rest with MPs, either through a vote in a committee or - if any MP on that committee insists - a vote by the entire Commons.

Last night, the Home Office made clear it would seek the Commons vote as soon as the four-month consultation ends.

A spokeswoman said: "There is a lot of appetite to get on with this as quickly as we can. It is not fair on any force to have a long period of uncertainty."

Cleveland Police, together with Teesside MPs, have fought for the North-East to be split into two "city regions", one combining Cleveland with the southern part of County Durham.

But the idea of splitting Durham has been ridiculed by the county's MPs, who are confident that neighbourhood policing can survive the creation of a regional force.

Mr Clarke said it was the clear conclusion of the study unveiled yesterday, carried out by Her Majesty's Inspectorate of Constabulary (HMIC), that a single North-East force was necessary.

HMIC had studied how best to deliver effective policing, as well as "affordability, organisational resilience and impact on Criminal Justice Service partner agencies".

The Association of Police Authorities (APA) has claimed the nationwide cost of mergers could reach £1bn, a sum dismissed by the Home Office, although it has failed to put forward its own figure.

A spokeswoman said the up-front costs would be easily outweighed by the long-term savings of cutting the number of forces and denied the burden would fall on council taxpayers.

She said: "We are saying to all the areas further assessed by HMIC that we will give them some start-up money if they agree to work with us to achieve these mergers."

Mr Clarke said he would meet the North Yorkshire chief constable and police authority chairman in the next few weeks, ahead of a decision there.

Two options are on the table - a single Yorkshire and Humberside force, or a merger of North Yorkshire with the West Yorkshire force.