Police and prosecutors need "to undertake radical change" in the way they handle rape complaints after an independent report highlighted the "overwhelming burden" on police staff, with "high levels of anxiety" at every stage of the process.
Metropolitan Police Commissioner Sir Bernard Hogan-Howe said today's review of rape investigations in London by Dame Elish Angiolini "shines an honest light" on failings in the service.
The review, which has involved discussions with rape victims and police over the course of a year, has made 46 recommendations to address areas including resourcing, improved training, enhanced victim care and changing the law regarding alcohol and consent. It also states that the system risks being "overwhelmed" by increased reporting of rape.
Dame Elish said: "Some of the recommendations will require a willingness to undertake radical change in the approach to these cases."
She said successive governments had "actively promoted" the increase in reporting of rape.
"There is an urgent need to ensure that the system is not overwhelmed because of a failure to fund the positive outcome of that policy."
The 161-page review found a 68% rise in rape and penetrative offences recorded by the Met from 2005/6 to 2013/14. However, there was only a 17% increase in offences charged within that time, the figures show.
The report states: "Whatever the reason, it is clear that the increase in reporting is putting an overwhelming burden on staff and concern is expressed about the Metropolitan Police Service's ability to effectively manage its increasing workload."
The review was also concerned about "the impact of excessive workloads on the effectiveness of both police and prosecutors, on delay and on police and prosecution staff welfare".
It said "high anxiety levels" were observed in both the Met and the Crown Prosecution Service (CPS), which it predicted would only worsen as staff struggle to meet increased levels of crime reporting.
The report found officers with the force's Sapphire rape investigation team had an average of 15 live cases at one time.
One officer told the report the number was "dangerous", while another described the volume of criminal investigations it had to deal with as "virtually nonsensical".
Dame Elish said the Government would be asked to consider amending sex offence laws so that the impact of severe intoxication - such as alcohol - is embedded in legislation.
Current laws do not provide a definition for whether an alleged victim is "incapable", meaning it is a matter for a jury to decide whether the complainant is so intoxicated as to be incapable of granting consent for sex.
Speaking at the report launch at New Scotland Yard this morning, Sir Bernard, Britain's most senior policeman, said the Met would give the same priority to sexual offending as it does to counter-terrorism.
"We have to give this area higher priority," he said.
"What we intend to do in three areas is give the highest priority to the new demands we are facing in the future - the first is around counter-terrorism, the second is around cyber crime, and the third is this area, sexual offence reporting."
He said the Met would need to recruit "a few more hundred" officers to deal with the volume of sexual offence reports.
"It's clear we need to do something - we cannot ignore this.
"We have to acknowledge already we have lost 15% of our budget and we believe later this year we will lose a further 15%.
"There is no 'no-risk' option going forward, something will have to give. It's vital that we invest in this area more than we have before.
"We will look to Government to see if there is anything they can do to support us. But either way, we have got to get better in terms of sexual offence investigations and in terms of reporting."
Baljit Ubhey, chief prosecutor for the CPS in London, said: "Many aspects of the recommendations within the review have already begun, but we must never forget that the changes and improvements we make should all be working towards our goals of providing a better service to victims and holding perpetrators to account.
"I am confident that, by embracing the findings of the review and delivering this change, our service to victims of rape in London will improve."
Katie Russell, for the charity Rape Crisis England and Wales, said it was "encouraging" for the Met and CPS to "express such determination to improve the criminal justice experience for sexual violence survivors".
She said: "It should be noted, nonetheless, that this isn't the first time we've heard positive sentiments such as these from criminal justice agencies and it is imperative now that encouraging words are translated into real action and cultural change.
"Rape Crisis fully supports any call for increased resourcing to meet the unprecedented demand from sexual violence survivors since Operation Yewtree - the need for specialist, independent rape crisis support and advocacy has never been greater and sustained, dedicated funding for such services must be recognised by the Government as an urgent priority."
Karen Froggatt, director at charity Victim Support, described poor handling of rape cases as "unacceptable".
She said: "Rape victims fear they will not be believed or their case won't be investigated properly, so the person who raped them will never be charged with a crime. That has serious consequences if that rapist goes on to attack another person.
"Consent is about much more than if someone said 'no', so the circumstances surrounding the incident should be examined carefully from the perspective of the victim.
"Any sexual offence can have a devastating impact on a victim's life - it's vital that they have confidence to go to the police so that they get the justice they deserve.
"In addition to the recommendations in this report, victims want to be offered therapy at the earliest opportunity. There is no reason to make them wait until after a trial."
Sarah Green, acting director of the End Violence Against Women Coalition, described Dame Elish's findings as "clear and incisive" and called on the Government to recognise the need for further police funding.
She said: " We hope the Government responds and acts to ensure that all parts of the criminal justice system are fit to pursue justice for every person who reports rape. We hope police and prosecution service leaders take to heart the findings and change their practices where they need to.
"Beyond this, we must recognise that the vast majority of survivors of rape still do not report it to the police. We must ensure there are adequate support services in our communities available whenever a survivor seeks them out."