Government spending on police force pensions is "unaffordable" and not "fit for the modern world", a report has claimed.
A report from the Policy Exchange claimed that £1 in every £7 spent on the police goes towards pensions, adding up to £2.5bn per year.
The Police Federation said it is negotiating reform to police pensions with the government.
Police Officer Pensions: Affordability of current schemes claimed that the cost of police pensions has increased by 79% in real terms, from less than £1bn a year in 1995/96.
Public spending on police pensions increased from £951m in 1995/96 to £1.9bn in 2009/10, which could have paid for 17,500 more officers, the report claimed.
The increase in life expectancy and the fall in active members of the pension scheme is to blame for the rising cost, the report claimed.
Report author Edward Boyd said: "We desperately need a new police pension scheme fit for the modern world.
"Without reducing costs, police officer pensions will become unaffordable for taxpayers and for officers themselves."
The report comes as the government continues to negotiate with unions over reform to public sector pensions.
Reforms include increased employee contributions, later retirement dates and a move from final salary to career average schemes.
The Policy Exchange recommended the government implements some of the general public sector pension reforms proposed by Lord Hutton in March 2011, such as creating new career average schemes and raising retirement ages for police officers.
It is illegal for police officers to join a trade union or to be affiliated with one in any way, and so they are unable to take strike action.
However, Simon Reed, vice-chairman of the Police Federation, the representative body created by the government, said: "As part of staff side of the Police Negotiating Board we are currently in discussion with the official side about the pension proposals as outlined in the Hutton Report.
"It is therefore strange, but perhaps not surprising, that Policy Exchange should decide at this point to promote their views on this matter."
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