The number of potential sexual exploitation cases involving children has risen over the last year, according to a senior police officer.

Detective Chief Inspector Dave Newsome said more referrals were being made to Hertfordshire Constabulary and Hertfordshire County Council because of greater public awareness about the issue.

Referrals are made to HALO when there are concerns about a child’s welfare and this sparks an investigation by Hertfordshire Constabulary.

Data presented to the Children’s Services Cabinet Panel at Hertfordshire County Council showed there had been 136 referrals to the multi-agency team set up to tackle the issue in the county between 1 April 2013 and 20, August 2014.

Over the same time period, 157 children or young people have been protected.

Detective Chief Inspector Dave Newsome said: "What we have seen over the last year or so, is a steady increase in the number of referrals to the police and local authority regarding child sexual exploitation.

"There is more media reporting and more public awareness of child sexual exploitation and part of that is we are trying to raise the issue so people know what the warning signs are.

DCI Newsome added that the unit has seen instances where children were "part of small groups and were being subjected to sexual exploitation" and the unit has also seen organised crime groups who organise child sexual exploitation, but stressed incidents of this kind were rare in Hertfordshire.

The number of referrals from Watford was the third highest across the county- with 14 per cent of referrals coming from the town.

Eight percent of the total referrals to HALO came from Three Rivers, while seven per cent came from Dacorum, which includes Kings Langley and six per cent from Hertsmere.

But DCI Newsome said the increased number of referrals in Watford was a reflection of the town’s larger population and said it "is to be expected".

He said: "In Hertfordshire, there are two or three more densely populated towns.

"The number of incidents we became aware of are higher in the towns than in more rural districts.

"We are not seeing a significant problem in Watford but the number of incidents are higher than other areas in the county.

"When you look at the density of population, it is to be expected.

County-wide, 40 per cent of the referrals to this multi-agency team come from Hertfordshire Police, 27 per cent come from Children’s Services, while seven per cent came from schools or other educational establishment.

Two per cent of the 136 referrals came from the victims themselves.

There are a number of signs associated with child sexual exploitation - including young people staying away from home, having significantly older friends and being given expensive gifts.

Other signs include self-harm, substance abuse, physical injuries and repeated sexually transmitted infections.