Rank-and-file police have attacked speed cameras for destroying the relationship between officers and law-abiding citizens.
Police say speed cameras lack an officer's 'power of discretion'
The Police Federation, which represents 136,000 officers, said officers are facing a backlash over the cameras.
"There is a general perception that it is a money-making exercise," federation chairman Jan Berry said.
The federation backs accident blackspot cameras, but wants an audit to assess if all existing cameras are needed.
The government says around 4,500 speed cameras are in operation, and Home Office figures show the number of fines rose from 1.1 million to 1.5 million between 2001 and 2002.
"We want some assurances that the cameras are being put in for safety issues. The government is going to have to demonstrate that in some way," Mrs Berry said.
"I believe some cameras are there as a revenue generator. I think police get the blame for that.
"I think it has been quite destructive - middle England will continue to pay their fines but others don't.
"There are concerns that large numbers of unpaid speeding tickets are being written off without any follow up."
The AA Motoring Trust's Andrew Howard said: "Maintaining public support for traffic policing is essential.
"While three quarters of drivers still support speed cameras, there has been growing concern that revenue raising has become the reason why many cameras are placed where they are."
The speed camera boom has been accompanied by a fall in traffic officer numbers.
But the Police Federation argues that speed cameras lack an officer's power of discretion.
"I don't think you can remove the human element from policing and replace it with a camera," Mrs Berry said.
"If you are going 35mph at 2am in a 30mph area and there is no other traffic on the road it would be extremely unusual for an officer to give you a ticket - a speed camera doesn't have that discretion."
The Police Federation also points out that cameras do not deter drink drivers, nor can they detect underage or uninsured drivers, those not wearing seatbelts, without a licence or in possession of drugs or guns.
"Technology is brilliant but it has to be used in a balanced way," Mrs Berry said.