Eighty-Five per cent of reported rape cases in Sussex collapse before making it past the stage of a police investigation.

Figures released under the Freedom of Information Act reveal instances where rapes may have taken place but the cases were dropped because of insufficient evidence; the withdrawal of allegations; and cases in which police decided no crime occurred.

Despite heavy criticism in recent years about the extremely low conviction rates for rape, the revelation shifts the spotlight from jurors to the police and Crown Prosecution Service (CPS).

An investigation by The Argus reveals that: Reported rapes in Sussex last year reached 418 - 20 fewer than the year before. The figure means that, on average, a woman reports a rape to police every 21 hours.

Hundreds of cases are dropped either by the police or the CPS while many are downgraded to less serious offences.

Official figures show that despite 856 rapes reported to police over the past two years, just 129 men were charged with rape.

The reasons for investigations being dropped were not given but national research shows more than a third are dropped for lack of evidence, despite most incidents being reported within 24 hours.

Meanwhile almost ten per cent of reports were dropped because they were deemed to be false allegations.

Liz Kelly, the UK's leading researcher of rape, said a culture of scepticism among police was partly to blame nationally.

She said more than a third of cases dropped are due to complainants declining to complete the investigation, which campaigners say is due to a lack of sexual assault referral centres providing support for rape victims.

The Brighton branch of national rape victim charity Rape Crisis was closed in 2005 because of lack of funding and national co-ordinator Louise Rogers said that every year another two shut.

"We only have 50 centres in England and Wales, which is about one per half a million women. It's desperate."

Jessica Taylor, of Safe as Houses, an east Brighton group dealing with domestic violence, said the closure of Rape Crisis in Brighton meant they were now often supporting rape victims.

She said: "We're stretching our remit but we'll never turn a woman away.

"Although there is a rape suite at the police station, it doesn't provide individual support and specialist advice."

Detective Superintendent Russ Whitfield, of Sussex Police, said: "We are in discussions with the health sector regarding the introduction of sexual assault referral centres to accommodate rape victims."

But he said the nature of the crime made it difficult to prove beyond all reasonable doubt and most cases weredropped before the CPS received the file.

Sarah Jane Gallagher, chief crown prosecutor for Sussex, said: "We don't see all the cases reported.

"The police are only required to refer to us if a case passes a threshold test."