By James Landale
Deputy political editor, BBC News
Ministers say it is up to forces to choose how to spend their money
The Conservatives say ministers are planning to reduce the number of front-line police, despite a pledge to protect them from spending cuts.
A Home Office study of nine forces has concluded that savings could be made by using more civilian staff.
Civilians can be used for roles such as keeping custody suites secure and advising households on security.
The Home Office said it was for individual chief constables to decide how to make efficiency savings.
The Tories say that any increase in civilian staff would automatically imply a reduction in uniformed officers because the government has promised merely to maintain current spending, not increase it.
The report, by the National Policing Improvement Agency (NPIA), said that "achieving financial savings and efficiency improvements whilst improving customer satisfaction... has been enabled through the introduction of new processes, which given financial constraints, is only possible through the introduction of new roles and through staffing these roles with police staff rather than officers".
The Conservatives also claimed Police Minister David Hanson told a conference - where the report was launched - the government was planning to remove the requirement on chief constables to maintain police officer numbers, despite giving them the same amount of money as before.
In a speech last week, Gordon Brown promised to protect police spending and said there was "no reason" why police numbers should fall.
"Our commitment to protecting the record numbers of police officers and police community support officers is clear," he said.
In the pre-Budget report last December, the government promised sufficient money in the next comprehensive spending review to enable police authorities to maintain current numbers of police officers, PCSOs and other staff exercising police powers until 2013.
Shadow home secretary Chris Grayling accused the government of "blatant hypocrisy" for "going into an election promising to protect police numbers while working on plans to cut them".
'Blend of staff'
The Home Office said the NPIA report was merely providing suggestions to chief constables about how they could make their forces more efficient and that final decisions were up to them.
In a statement, Mr Hanson said it was "vital" police forces make the best use of the historically high levels of funding in the service.
"Getting the right blend of staff can help the efficiency drive by freeing-up officers to spend more time at the front line," he said.
"The final decision on the best mix of staff and officers to tackle the unique challenges of individual forces rightly rests with chief constables, and this report will be important in informing their judgement.
"The recent White Paper on the future of policing is looking further at how government and police forces can build on efficiencies to deliver responsive policing to the public, while offering value for money."