Four local forces would become one under the plan

Birmingham, Coventry, Dudley and Solihull councils have started judicial review proceedings to prevent the government starting the merger process.

Staffordshire, Warwickshire, West Mercia and West Midlands would form one "super-force" under the proposals.

The councils claim the consultation process was flawed. The Home Office has said it is considering objections.

The merger is part of a national plan which would reduce the number of forces from 43 to 24. The Home Office has said larger forces are needed to better tackle organised crime and terrorism.

Not enough debate

Council tax-payers in the West Midlands currently pay less for policing than those in other counties.

"One particular concern is that the effect of the proposed restructuring will lead to higher council tax bills," the councils said in a statement.

Chief Constable Paul West said the merger was being rushed through

The councils want the courts to intervene so the merger process does not begin next month.

They are seeking a 12-month period to allow further consultation to take place.

The merger plan has been strongly opposed by the West Mercia force, whose chief constable, Paul West, has said there has not been enough debate about the changes.

West Mercia is also considering starting judicial review proceedings and has until Friday to take a decision.

Staffordshire, West Midlands and Warwickshire forces are in favour of the merger.

But MPs from rural areas have voiced fears that the merger could see resources diverted to bigger cities, where crime rates are higher.

The Cleveland force in the North East began judicial review proceedings against the merger affecting them on Wednesday.

A Home Office spokeswoman said: "The Home Secretary will not make a final decision on whether to proceed with the merger until he has carefully considered any objections received.