Three police forces have been criticised by the police watchdog for "poor" handling of discrimination complaints.
The West Midlands, Greater Manchester and West Yorkshire forces were accused of "significant" failings in the way they dealt with allegations of discrimination, in an Independent Police Complaints Commission (IPCC) report.
The IPCC said the criticisms applied in particular to discrimination complaints brought by members of the public, which it said were "poorly handled from beginning to end".
Too many complaints about discrimination from the public were resolved locally - without a formal investigation - when it was not appropriate to do so, the report found.
The quality of the local resolutions was also poorer than that of formal investigations, it added.
Of 170 complaints from the public - out of 202 complaints in total examined by the IPCC alleging discrimination - 94 were investigated and, of those, no discrimination allegations were upheld, it said.
Yet overall, the three forces upheld between 11% and 13% of complaint allegations from the public, the report stated.
By contrast, more than half of the 32 investigations into discrimination allegations studied by the watchdog which had been raised by the police themselves were upheld, the watchdog found .
"We came across numerous examples that seemed to show that internally reported conduct is taken more seriously than complaints," the report said.
"Only internally reported conduct matters resulted in misconduct proceedings.
"This, combined with the number of complaint investigations where the officer was believed rather than the complainant, leads to the inevitable conclusion that an officer is more likely to be believed and taken seriously than a member of the public.
"This is further supported by the fact that a number of complaints that were withdrawn were not continued as conduct matters and ought to have been."
The IPCC said allegations of discrimination were "serious matters" and local resolution of such complaints was "unlikely" to be appropriate for most cases.
Of the local resolutions sampled by the IPCC, 42% were found to be unsuitable for this procedure.
The report found 60% of local resolutions and 44% of investigations did not meet basic standards, and this rose to two-thirds and a half in cases that were handled at local level, rather than by professional standards departments.
A lack of up-to-date training in diversity issues lay behind many of the complaints, the report said.
"The police in these force areas do not appear to have a good understanding of the diverse communities they serve," it said.
A "significant" proportion of the complaints the report sampled were against the roads policing division with street stops generating the next largest category of complaints.
The IPCC said 173, or 78%, of 223 allegations within the 202 cases examined were about race.
Its remit had been to look into the way the three forces dealt with allegations in relation to any kind of discrimination including race, disability, age, gender and sexual orientation.
From the details that were recorded, most complainants were male, Asian, and aged between 26 and 35-years-old.
In 48 of the 170 complaints, no ethnicity was recorded and in 46 cases the complainant's age was not noted.
The report has been released after an IPCC investigation published last July into the Met's handling of race discrimination complaints revealed significant weaknesses in complaints handling in general as well as concerns about the way it investigated allegations of racism.
The IPCC said it chose to examine Greater Manchester, West Yorkshire and West Midlands police forces as the next three biggest forces after London, in an attempt to see whether there were similar concerns outside the capital.
At the same time, the watchdog widened its scope of inquiry to cover all areas of discrimination.
The report will be used to inform a full review of IPCC guidance on dealing with allegations of discriminatory behaviour later this year.
Dame Anne Owers, chair of the IPCC, said: " Our findings are stark - generally complaints of discrimination made by members of the public are poorly handled from beginning to end - in relation to the way the complaint is investigated, the conclusions drawn and, importantly, the contact with the complainant.
"It is vital that police forces deal effectively with allegations of discrimination.
"For particular sections of the community, likely to be more distrustful of the police, or more vulnerable, or both, they are a litmus test of confidence in policing as a whole and of the police's understanding of the communities they serve.
"While we welcome the fact that officers are prepared to report and challenge their colleagues when it comes to discriminatory behaviour, allegations made by members of the public need to be handled equally seriously and dealt with effectively.
"Increasingly, complaints are dealt with by local officers, not specialist professional standards departments, and the quality of complaint handling at local level is clearly worse.
"It is clear that much more training and support is needed and we will continue to work with forces and other bodies to provide information, influence training and standards, and monitor outcomes."
West Yorkshire Police Deputy Chief Constable Dee Collins rejected the report's claim that the force did not have a good understanding of the communities it serves.
" What matters most to us is that people who complain have the confidence to contact us, knowing we will deal with matters fairly and professionally," she said.
"While we accept there are always areas for improvement and we really welcome the independent scrutiny of bodies like the IPCC, our current complaints system is undergoing significant improvement incorporating previous observations from the Crawford report as well as other feedback.
"We are very disappointed with the suggestion that we are 'failing at every stage'.
"However, we recognise there are some improvements to be made and we are well advanced with that work, significant changes having taken place since the time this data was collected.
"Furthermore, we refute the report's assertion that we 'do not have a good understanding of the communities (we) serve'.
"It is not our experience, or what we hear from the communities where our Neighbourhood Policing Teams are firmly embedded and have an excellent relationship and a real focus on local issues.
"West Yorkshire Police officers and staff have contact with thousands of people every day, often in distressing and difficult situations.
"The vast majority of those instances not only pass without complaint, but often result in positive comments and letters praising our people.
"Most West Yorkshire Police employees joined to serve the public and are totally committed to upholding the high standards we expect and aiming to make communities safe and feel safer.
"However, we understand there will be exceptions and want to assure individuals and communities that any allegation will be treated seriously and thoroughly investigated.
"Changes last year led to our professional standards department being strengthened and staffed by highly experienced investigators, together with the establishment of a complaints and strategy unit, to address a number of the issues that have been raised within the IPCC report.
"We have to have the best systems possible, where both the complainant and the officer or staff member have the opportunity to explore and understand what has happened, and to deal with the matter appropriately."
Detective Chief Superintendent Paul Rumney, head of Greater Manchester Police's Professional Standard's Branch, said: "The IPCC report is a clear cause for concern and I welcome the scrutiny placed on this important issue.
"The current system focuses on whether the behaviour that resulted in the complaint can be proven to have happened and in a vast majority of cases it simply comes down to one word against another, meaning many cases cannot be substantiated.
"That is why change and improvement must be made and that is why most of the recommendations within the report have already been implemented by Greater Manchester Police and our action plan will be shared with the IPCC.
"In addition to implementing these recommendations, there will now also be a review of how discrimination and other public complaints are handled.
"I am committed to ensuring the public has the confidence to make a complaint to us if they feel they have been treated inappropriately in the knowledge that their concerns will be thoroughly investigated to the highest standard, hence all allegations of discrimination will now be investigated by officers from our Professional Standards Branch.
DCS Rumney also pointed out that the GMP has been trialling body-worn cameras for staff dealing with public order, domestic abuse and other violence.
"The cameras have the potential to support complaints as well as disprove malicious allegations and the Professional Standards Branch would like to see the use of body-worn video extended," he said.
"I am pleased that our "co-operation and willingness to learn" has been acknowledged within the report and our commitment to implement change for the better is further reflected in the work the Force is doing with the Police and Crime Commissioner in relation to the introduction of an ethics committee and appointment of an independent ombudsman.
"We know there is a lot of work to be done but we are absolutely determined to make our system more accessible, timely and effective both for the public making complaints and the officers subject of them."
Deputy Chief Constable Dave Thompson, from West Midlands Police, said: "West Midlands Police recognises how we deal with complaints concerning discrimination is an important matter of public interest and one which has a direct bearing on community confidence in policing.
"We are constantly striving to improve our service to the public and will review the report in detail. We take complaints very seriously and do not tolerate discriminatory behaviour.
"The report draws conclusions across three forces. Within this there are variations in practice. West Midlands Police has been recognised as demonstrating strong performance in monitoring complaints to identify complainants from minority communities.
"There are however concerns over how our lower-level investigations are handled by our local policing units; and how we keep people informed about their complaints. We will review carefully and work with the Police and Crime Commissioner, community members and our staff networks to look again at how we can improve our work. We are absolutely determined to deliver a fairer and transparent service.
"A report of this significance does present opportunities for learning and insight. We are very disappointed the IPCC did not seek to properly engage with us about this work to enable the force to share its approach on improving complaints procedures.
"The report suggests the forces do not appear to have a good understanding of the communities they serve and we look forward to understanding how the IPCC have reached this conclusion."