Catastrophic cuts in police numbers mean that rank and file officiers are unable to do their jobs effectively, the Police Federation has said.
The Home Office earlier reported that police numbers are at their lowest level for 10 years after budget cuts forced constabularies around the country to make reductions in staff.
There were 135,838 officers in the 43 police forces at the end of September last year, the Home Office said - more than 6,000 fewer than the previous year and fewer than at any point since 2002.
More than 3,000 officers have been lost since last March alone. A further 423 officers were seconded to central services.
Only one force, Surrey, increased its officer numbers over the 12 months to last September, up 97 (5.2%) to 1,961.
The Police Federation, which represents rank and file officers, said that the cuts would necessarily make an impact on service quality.
"Regrettably, the dramatic decline in police officer numbers comes as no surprise to us as the service contends with a minimum 20% cut to budgets," said Paul McKeever, PolFed chairman.
"How can we possibly provide the same level of service to the public if we are losing thousands of officers?
McKeever added that with the Olympics around the corner it was the wrong time to make cuts.
"Today’s announcement is just the tip of the iceberg, as we will see even fewer police officers available as we embark on policing the biggest security event this country has ever seen, the Olympic Games.
"It is deeply disappointing that the coalition government’s decision to cut the police budget was taken purely for fiscal reasons, without any regard for the impact on public safety."
But the Association of Chief Police Officers said while the cuts were tough for the service to take, they would not necessarily lead to service cuts.
Greater Manchester Police Chief Constable Peter Fahy, the Acpo lead for workforce development, said: "This is a very difficult time for most police forces with significant reductions in staff and the challenge of managing redundancy and change programmes.
"Workforce morale is understandably affected by the pay freeze and increase in pension contributions."
But he added: "On the positive side many forces have started recruiting again or will do so in the next financial year.
"However, the effectiveness of policing cannot be measured by the number of officers alone but by reductions in crime and increases in public confidence.
"The service is realistic about the current economic crisis but will need to seek new ways of working and new approaches to reducing demand and cost as this loss of experienced staff continues."