Offenders will be more likely to get away with their crimes as police numbers are cut in the wake of the Government's spending review, a think-tank has warned.
Members of the public are likely to be at greater risk of becoming victims as falls in crime will be halted or reversed following a 6% reduction in the national funding grant this year and a 20% cut over the next four years, Civitas said.
A comparison of the number of police officers and the number of recorded offences per 100,000 people in European countries showed "a nation with fewer police is more likely to have a higher crime rate", it said.
But Policing Minister Nick Herbert has insisted there is not a "simple link" between police numbers and crime. "What we should be concerned about is how officers are deployed, whether they are available and visible to the public, whether they are there on the streets when the public want them," he said last month.
"Therefore, what matters is not the total size of the police workforce but the efficiency and effectiveness of deployment, how much bureaucracy is tying them up."
But the Civitas report, entitled 2011: the start of a great decade for criminals?, said reducing police numbers "could lead to an increase in the crime rate", saying its predictions were consistent with other academic studies that found more police were "associated with lower crime rates".
Its author, Nick Cowen, wrote: "It is plausible to suggest that police resources play an essential role in tackling crime. While police numbers and resources are far from the only contributor to police effectiveness, it seems highly unlikely that the swingeing cuts now being enacted will be made without significantly decreasing detection rates.
"The result will be that offenders will be able to engage in criminal acts with a reduced risk of being caught and sanctioned, making criminal acts less risky and more attractive for potential offenders. As a result, it is possible that recent falls in crime will be halted or even reversed. Members of the public are at greater risk of crime in the coming years."
He admitted that establishing a "causal relationship" was "notoriously difficult in criminology", but added that "crime rates have been consistently negatively correlated with key measures of police effectiveness".
The Police Federation of England and Wales, which represents rank and file officers, said the report should act as a wake-up call for the Government. Simon Reed, the federation's vice-chairman, said: "This Government cannot ignore the direct correlation between police officer numbers and the crime rate and must urgently reconsider the level of cuts the police service is facing over the next four years."