Complaints against the police rose by 42% in Northamptonshire in 2009-10, more than five times the national figure, a report has revealed.
The Independent Police Complaints Commission (IPCC) said 599 people complained in the county. Nationally complaints rose by 8%.
A complaint case can contain several allegations. In Northamptonshire, these rose from 505 to 703, the IPCC said.
Most allegations related to neglect of duty and incivility.
There was a rise of 150 to 209 and a rise of 119 to 141, respectively, in the two categories - known as "rude and late" .
A third category, assault, saw a much smaller increase of 56 in 2008-09 to 58 in 2009-10.
'Need to improve'
IPCC Commissioner for Northamptonshire, Amerdeep Somal, said: "Last year Northamptonshire experienced a substantial rise in the number of complaints and I will be discussing this with the force in due course.
"However, from experience, it is often the case that rises of this type are as a result of a more comprehensive policy towards recording complaints rather than necessarily falling standards of police behaviour.
"The number of 'rude and late' complaints highlights the standards expected of the police service and the need to improve how they interact with the public.
"However, while some aspects can be improved without cost, such as through better leadership, smaller police budgets will present a challenge around levels of service and public expectation."
Det Supt Peter Windridge, head of professional standards at Northamptonshire Police, said: "We are always looking to improve the ease and level of access the public have with the police and this includes being clearer about how they can make complaints.
"This in part will have contributed to the increase in the number of complaints.
"Whilst all complaints received in the last year were investigated, only 16 (3%) were actually upheld.
"We take every complaint seriously, looking at what has gone wrong and feeding that through to department heads and training units, so that we can make improvements and learn."