A postcode lottery in the way rape cases are handled by police has been highlighted by figures showing wide variations between forces across England and Wales, it is claimed.
Differences in the rate of recorded rapes, charges or cautions for the offence and records later declassified as a "no-crime" incident have raised fears of a "culture of disbelief" among some of the 43 forces covered by the data.
Among key contrasts, Northamptonshire Police had the highest rate of recorded rape at 34.8 per 100,000 adults in the year to March 2013, while Durham Police had the lowest at 9.8 per 100,000 adults. The average is 22 rapes recorded per 100,000 adults.
And Lincolnshire Police had the highest "no-criming" rate for adult rapes - that is, an offence initially recorded as rape, but then declassified - at 33%, compared with Cumbria, which had the lowest no-criming rate at 3%. The average no-criming rate is 12%.
Rape charities and women's rights groups said data, which was pulled together for the first time by the cross-Government, multi-agency Rape Monitoring Group (RMG), revealed disparities and attitudes which must be "urgently tackled".
Professor Liz Kelly, chair of the End Violence Against Women coalition, said: "The wide disparities between different areas' reporting, detection and 'no crime' rates may indicate that the culture of scepticism remains in some police forces.
"This is not a surprise to us. Our member organisations know how deep disbelief and victim-blaming goes in institutions and communities.
"But the police play a critical role enabling rape survivors to access justice, so these disparities and attitudes must be urgently tackled."
Katie Russell, spokeswoman for charity Rape Crisis England, said releasing the data reflected a commitment to transparency and scrutiny of police practice.
But she added: "Nonetheless, Rape Crisis is still extremely concerned by the persistently high levels of 'no-criming' today's data reveals, as well as by the huge disparities in statistics between different police forces."
She said that the figures show that little has changed since a 2012 report from Her Majesty's Inspectorate of Constabulary (HMIC), which highlighted concerns around inconsistent and inadequate recording and investigating of sexual offences.
"This leaves us wondering how many more reports it will take before we see a real and marked improvement in criminal justice for rape survivors," she added.
Elsewhere, the data reveals Durham Police had the highest "sanction detection" rate, that is the number of recorded adult rapes that result in a caution or charge, at 32%, while Warwickshire had the lowest at 6%. The average sanction detection rate was 18%.
Some 29 forces had a recorded adult rape rate below the average 22 per 100,000, while 21 forces have a below-average sanction detection rate.
Meanwhile, 16 forces had a higher than average no-criming rate for adult rapes, the figures show.
A recorded crime can be "no-crimed" where additional verifiable information determines no crime has been committed.
Asked if the figures triggered suspicions of a "culture of disbelief" in some forces, RMG chair and HM Inspector of Constabulary Dru Sharpling said: "We don't measure a culture of disbelief but it would raise a question in my mind about that issue."
Ms Sharpling said the HMIC report on Jimmy Savile revealed difficulties in rape victims coming forward to police and "lack of confidence" was one of the issues.
She added there may be a range of "other explanations" for the disparities between forces but questions over disbelief had to be raised.
The number of recorded rapes, for both adults and children under 16 years, has steadily increased since March 2008, the figures show.
In the last financial year to March 2013 there were around 6,000 recorded rapes of children and roughly 10,000 recorded rapes of adults in England and Wales, up from around 5,000 and 6,000 respectively in 2008/09.
Humberside Police had the highest recorded child rape rate at 106 per 100,000, compared with Hertfordshire, which had the lowest at 28. The average for England and Wales is 59.5 per 100,000.
Surrey Police had the highest sanction detection rate for child rapes at 55%, while Essex had the lowest at 13%. The average in England and Wales was 31%.
Given the relatively low number of recorded crimes and "no crimes" for child rape, small changes to the data could have a large impact on forces' no crime rates.
Crime prevention minister Norman Baker said the data does not suggest that incidents of rape and sexual violence are increasing, but that " victims are more confident that reporting such incidents will now be taken more seriously".
He went on: "But we need to make sure that victims of rape have total confidence in every stage of a criminal justice system.
"Transparency and accountability are at the heart of our approach.
"The release of this comprehensive set of data means police forces and police and crime commissioners will now be able to monitor their performance and drive improvements so that more victims come forward and more perpetrators are brought to justice."
The RMG, set up in 2007, is made up of representatives from the Association of Chief Police Officers (Acpo), the Attorney General's Office, the Child Exploitation and Online Protection Centre, the College of Policing, the Crown Prosecution Service, Her Majesty's Crown Prosecution Service Inspectorate, the Home Office, the Mayor's Office for Policing and Crime and the Ministry of Justice.
Policing practice developer Helen Hopwood, who represents the College of Policing on the RMG, said n ational policing guidance, known as Authorised Professional Practice (APP), on investigating rape and sexual offences is currently being updated as part of a wider piece of work and will go out to consultation in April.
She said: "The datasets that have been published today highlight inconsistencies between forces about the outcome of rape investigations. This must be tackled.
"The College of Policing will work with the national policing leads and forces to ensure developments in training and practice in rape investigation are implemented for the benefit of victims of rape."
National policing lead for crime recording Chief Constable Jeff Farrar said: " To build people's confidence in the way police deal with sexual offences, it is my view that allegations of rape should be recorded as a crime when it is reported without question or challenge.
"This will help provide a consistent approach across the country that is supportive and victim-centred. As national lead I will raise this issue in the Crime Statistics Advisory Committee to see if there is more that can be done to improve consistency across forces.
"There was a particular call from policing and crime commissioners to have this data, and what it will allow is a robust and well-informed discussion at a local level as well as an opportunity for us to challenge ourselves at a national level around achieving a consistent policing response to victims of rape."