Sexual offences against children are on the rise in England and Wales, with the National Society for the Prevention of Cruelty to Children (NSPCC) saying there was a one-third increase of recorded cases between 2013 and 2014.

There were 31,000 offences recorded in the year up to April 2014, up 8,500 on the previous year. These figures, said Peter Wanless, the NSPCC's chief executive, were "a fraction of the true number of victims, because some endure an agonising wait of many years before telling anyone - and others never reveal what has happened to them".

According to the figures, compiled by a Freedom of Information request, most of the victims were aged between 12 and 16.

But 8,282 were younger than 11, the charity said. Of those, 2,895 are estimated to be aged five or under, including 94 babies. And 24,457 of the reported abuse cases were against girls, with 5,292 against boys. The Metropolitan Police - Britain's largest police force - recorded the highest number of sex crimes against children, with 3,523.

Scotland and Northern Ireland also saw increases in recorded cases.

In 2012/13, the same research showed 22,654 cases were recorded by 41 police forces. All 43 forces in England and Wales responded in the latest study.

The NSPCC said the total had largely remained steady until this year's figures, and that the 38% rise was the biggest increase in six years of requesting the data.

The number has now increased by almost 50% since 2008/09.

Jon Brown, from the NSPCC's sexual abuse programme, told the BBC there was not enough support available for children who had been sexually abused.

He said: "Their concerns need to be taken seriously and acted promptly upon. Through the court process, they need to be supported and there are some real gaps there, and then there's a huge gap in the amount of help and therapy that's available for children who have been abused."

Brown added that the NSPCC estimated that there was a shortfall of 50,000 places across the UK for children who needed treatment, having been sexually abused.

The figures are published as the NSPCC launches its third annual "How Safe Are Our Children?" report at the charity's annual conference in London.

A government spokeswoman said children must be protected from "systemic and appalling cases" of abuse such as those seen in Rotherham, Rochdale, Oxford and elsewhere.

She said: "We have given child sexual abuse the status of a national threat so that it is prioritised by every police force, will shortly launch a new child sexual abuse task-force and centre of expertise to improve local responses and we have provided £7m funding to organisations that support victims.

"It is encouraging that police figures show more victims are having the confidence to come forward and report these often ignored and under-reported crimes."