Plans to boost civilian staff in the police have dominated Home Secretary David Blunkett's visit to the Police Federation conference.
The home secretary says community support officers are popular with the public
He said civilian community support officers (CSOs) were a "non-negotiable element of modern policing".
His staunch defence of CSOs came as a leaked report suggested the officers could be used to operate speed cameras and administer breath tests.
The Inspectorate of Constabulary report says CSOs could be given other powers.
These include allowing CSOs to carry out investigations of minor incidents and detain, escort and interview suspects.
Another proposal would allow store detectives and private security staff to deal with offences of shoplifting.
Delegates at the Police Federation Conference in Bournemouth were told by Mr Blunkett: "I as Home Secretary would never, ever want to go forward and recruit more CSOs if it were at the expense of reducing the record number of trained, uniformed police that are represented at this conference."
He also said he did not think CSOs should investigate crime.
"The investigatory role falls to either the properly trained officer or the
specialist civilian investigators we already have in place," said Mr Blunkett.
The chairwoman of the federation, Jan Berry, said the public would become confused if police powers shifted to civilians.
She said: "The powers of detention and search are areas which should be reserved for
police officers who are accountable and independent."
She said that although there were 3,5000 CSOs in England and Wales who patrol streets offering a visible reassurance to the public, there was no research to show how effective they were.
Frontline officers are concerned about police reform
"Home Secretary, think very carefully before you throw the Bobby out with the
bath water," said Mrs Berry.
"You are going too far, too fast and - trust me - there will be a price to be
The federation represents 136,000 frontline officers.
The inspectorate said that encouraging more civilians to join the police had been a vehicle for recruiting large numbers of women and ethnic minority staff, but the service "has not fully exploited the benefits that this route offers".
It says the service needs to be aware of the danger of "ghettoisation" - predominantly white male police officers, supported by a group of largely minority ethnic colleagues in less well-paid roles.
Home Office minister Hazel Blears was jeered by delegates on Tuesday when she defended their use.