Scotland has been hit by an epidemic of phone and online sex crime with girls under 16 making up three quarters of its victims.

New figures, described as a “wake-up call” by campaigners, show children bearing the brunt of a surge in “indecent communications” enabled by the web.

Scottish Government researchers found such crimes were largely committed by older boys on young girls, with the average perpetrator aged just 18 and victim only 14.

The sheer scale of the rise in such "cyber sex offending" - overall numbers of such crimes recorded have jumped 50 per cent in just three years - has sparked calls for a root-and-branch review in the way such issues are dealt with in schools.

Rape Crisis Scotland's chief executive Sandy Brindley said booming reports of online sexual crime was "significant and worrying".

She added: "This is a wake-up call: now more than ever we can see the urgent need to challenge this behaviour by undertaking prevention work with young people across Scotland.

"In our work with young people in schools, they tell us of everyday sexual assault, harassment, and the sharing of intimate images without their consent."

The new numbers emerged after Justice Secretary Michael Matheson asked analysts to drill down in to why a once obscure catch-all category of offending "other sex crimes" was rising in statistics.

The latest national crime statistics show a drop in overall offending, which is at the levels of the early 1970s.

In the last decade violent crime has halved - although it rose six percent last year.

However, sex crime, including "other sex crime", has soared in the last decade.

The number of rapes recorded in 2016-17 was up, but only very slightly.

However, the category of "other sex crimes", which includes many cyber-enabled offences, rose by 50 per cent from 2,901 in 2013/14 to 4,360 by 2016/17.

The research estimates around half of the growth in all sexual crimes recorded by the police over the period is due to growth in cyber-enabled offences.

Analysis shows the growth has been driven by large increases in the crimes of "communicating indecently" (up from 605 to 1,166) and "causing to view sexual activity or images" (from 229 to 1,030), with these categories now accounting for 20 per cent of all sexual crimes.

Researchers looked at in more details at the make-up of victims and perpetrators of two offences, communicating indecently or causing to view indecent images, where the offences were "cyber-enabled", , carried out using a phone or computer link. It was specifically for these crimes that victims proved to be young, with a median age of 14 and nearly three-quarters of those affected under 16.

For all the entire category of "other sex crimes", nearly four-fifths of victims were female and three-fifths were under 16, while the vast majority of perpetrators were male.

In 2016-17 the victims and perpetrators were strangers in 42 per cent of cases.

Mr Matheson said: "The sexual crimes research makes clear that more work is required to understand why particularly young males are behaving in this way and to prevent sexual offending.

"While we have taken considerable steps in this area, such as our recent 'intimate images' campaign, the national action plan on internet safety and our 'Equally Safe' strategy, I am bringing together an expert group to identify further steps needed to better-tackle and ultimately prevent such offending."

Prosecutors and other justice sector professionals are concerned at the number of children and young people ending up in trouble over cybersex crime.

Solicitor General Alison Di Rollo QC, who recently hosted a summit on educating young people on sexual crimes, said: "Too many children and young people are coming into contact with our justice system as a result of sexual offending, and we know that technology has an increasingly significant part to play.

"I am delighted that this new expert group will now build on the success of the summit, and acting on the key messages we heard, identify and take the next steps to inform and protect our young people."

The research on sex crimes was published alongside figures which showed recorded crime in Scotland dropped 3 per cent from 246,243 in 2015-16 to 238,651 in 2016-17 - the lowest level since 1974.

Non-sexual serious violent crime increased by 6 per to 7,164 while sexual crimes also rose 5 per cent to 10,822 and crimes of dishonesty, fire-raising and vandalism all decreased.

The Scottish Conservatives highlighted a drop of 1.6 percentage points in the clear up rate for all recorded crime to 50%.

Tory Liam Kerr MSP said:"The fall in clear-up rates will be immensely concerning to people right across the country.

"We're now in a situation where criminals know they literally have a 50/50 chance of getting away with their illegal activity."