The Chief Constable of West Mercia Police has condemned proposals for a regional super-force in a meeting with the Home Office.
Paul West, who has led the constabulary for two years, told Ministers: "It is undoubtedly the wrong model for the people of West Mercia."
He was speaking to Home Office Minister Fiona Mactaggart at Westminster.
A merged "strategic regional" police force would cover five million people across the West Midlands, replacing the four existing forces.
It follows an official review which warned smaller forces did not have the resources to tackle organised crime or the threat of terrorism.
West Mercia, recently named the best force in the country by official inspectors, covers Worcestershire, Shropshire and Herefordshire.
The force has told the Home Office it would prefer to remain independent, but Mr West has previously avoided publicly criticising the alternative proposals.
However, he spoke out when he had the chance of an impromptu meeting with a Minister in a House of Commons coffee bar.
He had been summoned to London with Paul Deneen, chairman of the West Mercia Police Authority, for a debate on the future of the force.
But the debate, at 11am yesterday, was cancelled when the MP who asked for it, Philip Dunne (Con Ludlow), arrived two minutes late.
Mr Dunne apologised but the chairman, Conservative MP Nicholas Winterton, refused to allow the discussion to take place despite his pleas.
Mr West, Mr Deneen and MPs instead went to the cafe in the House of Commons, along with Ms Mactaggart.
The Chief Constable told her: "West Mercia is the best performing force in the country.
"With the regional structure proposed it would not be possible to serve our communities in the same way."
He urged the Minister to consider other type of reforms which would allow smaller forces like West Mercia to remain independent.
"There is a very strong feeling that the pace of this, that has been imposed, is outrageous," he said.
Ms Mactaggart responded by highlighting the need to fight the threat of terrorism.
The drive to reform Britain's police has been prompted by an independent report by Her Majesty's Inspectorate of Constabulary, which warned forces with fewer than 4,000 officers were ill-equipped to deal with today's challenges.
As well as a massive regional force, the Home Office has said it is willing to consider merging West Mercia and Staffordshire Police, and merging Warwickshire and West Midlands Police.
Mr Dunne was under fire from Labour MPs for arriving late to his own debate.
Mike Foster (Lab Worcester), who had been hoping to speak in the discussion, said: "It is an absolute disgrace. I'm appalled at the way the police have been treated. To call a debate and not turn up for it is an absolute sham.
"It is an important issue about West Mercia Police, and I was here ready to make a contribution."
Mr Dunne said he was delayed when his printer broken down.