Crunch talks are to be held on Monday to clear the air on the financial implications of West Yorkshire Police merging with three other forces.

Home Secretary Charles Clarke wants to create a "superforce" by amalgamating West Yorkshire, North Yorkshire and South Yorkshire & Humberside, which is likely to be done by April 2008.

He has demanded a response by next Friday from the four police authorities, including West Yorkshire, which has always insisted it wants to remain independent.

West Yorkshire Police Authority yesterday discussed whether to agree or write to the Home Secretary declining to request a voluntary merger.

But it postponed the decision for a week after members expressed concern they had not been given enough information about the impact the merger would have on finances, council tax precepts and how the force would be organised.

The authority's financial chiefs are travelling to London for talks with Home Office officials on Monday. Authority officials are holding a meeting with the head of the Policing Referral Unit.

The chief constables of the four forces, including West Yorkshire's Colin Cramphorn, will also meet to discuss the issue.

There was anger at yesterday's meeting about a Home Office website which suggested West Yorkshire was not effective enough in dealing with major crime to remain as a stand-alone force.

But Mr Cramphorn said two TV programmes last week - about the Ripper hoax and Operation Recall, which reviewed unsolved rape cases - were examples of how effective West Yorkshire Police was.

He said the "high jump bar", measuring the standards of policing nationally, seemed to be moving up or down in different regions.

Mr Cramphorn said the force had not been given a revised assessment by HM Inspectorate of Constabulary. "It is beyond a veil where we hear a voice but nothing more in terms of what the assessment is based on," he said. "No-one spoke to us about it until last week."

Home Office consultants have reviewed the financial submissions and say the cost of setting up the new force would be £39m, compared to the £52m figure submitted by the authority last December.

The consultants say annual estimated savings had increased from £4.4m to £18m, which included £8.4m from staffing reductions.

Mr Cramphorn said: "The consultants, in reaching their savings, estimated a reduction of five per cent in police staff - more than 330 for us and more than 700 across the region. We have an issue about that."

He said three chief constables and three deputy chief constables would be lost in a merger but they were seeking clarity from the Home Office about what would happen to assistant chief constables.

Authority chairman Mark Burns-Williamson said it was the most important change in policing they were likely to see and they needed more information on finances, precepts, protective services and the strategy of other forces.

Member Melvyn Smith said two other police authorities were thinking of taking proposed mergers to a judicial review.

But he added: "As a magistrate, I don't think there is a cat in hell's chance of winning a review."

The authority will meet again next Friday.