More than 300 children in Norfolk were victims of sex crimes including rape, incest and abuse through prostitution and pornography, last year according to shocking new figures.

The scale of sex crimes against children in this country, which equate to 444 attacks a week or one child being abused every 20 minutes, emerged after a Freedom of Information request by the NSPCC.

The NSPCC, which sent FOI requests to the 43 police forces of England and Wales, showed that in Norfolk, of the 321 child victims of sex crimes 286 were girls and 35 were boys, while in Suffolk there were 386 child victims of sex crimes and in Cambridgeshire 439 in Cambridge.

The charity says that more than 400 sexual assaults against children were reported to police forces in England and Wales every week last year (2010-2011) with fewer than one in ten resulting in a conviction.

More than a fifth of the 23, 097 victims were of primary school age and almost 1,500 were five or under. A total of 14, 819 offences were committed against 11 to 17-year-olds and girls were six times more likely to be abused than boys.

The NSPCC is calling on schools and parents to educate children about staying safe and reporting abuse as well as urging the government to support the provision of therapeutic services for all child victims of sexual offences and treatment programmes for offenders.

Dan Russell, regional head of service for North London and East of England at the NSPCC, said: 'Many of these distressing offences are committed on extremely young and helpless children, who may not understand what is happening to them and are unable to ask for help.

'The NSPCC is doing what it can by using information like this from the police to tailor our treatment services- different approaches are needed depending on the age of the child. We are also pioneering new programmes across our region to tackle sexual abuse of children, including our Schools Service which aims to visit every primary school in the county over two years.'

Dr Caroline Ball, independent chair of the Norfolk Safeguarding Children Board, said it was a 'serious problem'.

She said: 'It's quite impossible to tell from the figures whether there's been an actual increase in incidents, which I suspect that there has, or whether, particularly with the younger children, they are feeling more able to disclose what's happening to them.'

She added the NSCB was working closely with partner agencies to help raise awareness of child sex abuse and of the symptoms of it.

A spokesman for Norfolk Constabulary and also Suffolk Constabulary said: 'We recognise that coming forward can be a difficult step for victims and we will investigate cases that are reported to us with sensitivity and whatever the timeframe. Each report is taken very seriously and thoroughly investigated in an empathetic and appropriate manner. We have specially trained officers who deal with victims of childhood sexual abuse, they also work closely with partner agencies to ensure all necessary support advice and guidance is available.'

If adults have concerns they should contact social services, police on 101 or call the NSPCC Helpline on 0808 800 5000. Children should call ChildLine on 0800 1111.