Less than one in 10 rapes and sexual assaults in Newham reported to the police resulted in a conclusion within one year.

There were 399 reported sex offences between January 1 and November 30 in 2011.

After 158 complaints of rape were made during this period, a dozen people were charged, while the remaining 146 cases were still under investigation as of January this year.

A total of 211 reports of sexual offences, not including rapes, were made last year. Twenty-four people were charged and six cautions handed out.

And compared to 2010, the number of people charged with committing a sexual offence dropped significantly, from 91 to 36.

The Nia project, which is based in Hackney, supports female victims of violence and assault in east London.

Chief executive Karen Ingala-Smith said the time it took to investigate rape allegations sometimes made it frustrating for users of crisis centres like hers.

She said: “It’s very difficult and it adds to the dissatisfaction that some women have with the criminal justice system.

“I think there is still a hell of a lot to be done.

“You see articles in the news all the time about women who have had unsatisfactory experiences with the police and the CPS.

She added: “I also think the myths perceptions about young women and what they should wear and where they should go are still here.

“There needs to be training for all police. Officers also need support from rape crisis centres.”

Between January and the end of November 2010, police dealt with a total of 457 rape and sex offences.

One in five of these resulted in a charge, 12 people were cautioned, and two investigations were dropped.

A Met Police spokesman said the year on year reduction in reported sex offences could be put down to a better complaince with Home Office recording guidelines. This has seen more initial complaints recorded and investigated as a crime.

He said: “Any allegation reported to police is subject to a full investigation which exhausts all possible lines of inquiry.

“We would encourage victims to report offences to police or the Havens (specialist sex assault victim centres) regardless of the potential outcome of any investigation, so they can receive the necessary support and care so important following such a traumatic incident.”