Complaints against police in Lancashire are less likely to be formally investigated than anywhere else in the country, new figures show.
The police watchdog has raised concerns over wide inconsistency in the way forces handle complaints.
Figures published by the Independent Police Complaints Commission (IPCC) show Lancashire Police investigated just one in 20 complaints last year.
Almost three quarters were dealt with under the informal local resolution process, while 273 of the 1,782 complaints were withdrawn.
Dame Anne Owers, chairman of the IPCC, said: “These figures for England and Wales show a complaints system that is both over-complex and inconsistent, and is clearly failing to satisfy a significant number of complainants.
“Chief Officers and Police and Crime Commissioners should look closely at the figures for their own forces to satisfy themselves that complainants are being treated fairly and well.
“However, the underlying problem is the system itself.
“We welcome the fact that the government proposes to bring in legislation to simplify and streamline a system that at present satisfies neither those who need it nor those who have to operate it.”
IPCC figures show Lancashire Police upheld 26 per cent of complaints it investigated, more than double the national average.
The force completed 168 appeals against its handling of complaints last year and upheld 18 per cent. The IPCC handled 55 appeals relating to Lancashire Police and upheld 28.
A Lancashire Police spokesman said: “We are committed to ensuring that high professional standards are maintained in all our interactions with the public and we are focused on delivering a quality of service and getting it right first time.
“On the rare occasions when this does not happen we try to resolve any issues as quickly as possible and to find out what went wrong and why so that we can fix it.
“We take all complaints seriously and ensure that they are investigated fairly and thoroughly. We are never complacent and act on all forms of feedback, using it as an opportunity to make improvements, which will continue to be the focus of the Constabulary.”