A NATIONAL child abuse investigation unit is being set up in Scotland to stem the rise in sexual exploitation.

Police and prosecutors will join forces with councils and charities to tackle the issue, with the new unit designed to improve the coordination and intelligence-gathering around abuse.

Mobile devices such as camera-phones, improved download technologies and sophisticated software to hide activity have led to a rise in child abuse, Assistant Chief Constable Malcolm Graham said.

Many offenders are "resourceful, intelligent and sophisticated in their pursuit of online offending", he said in a submission to Holyrood's Justice Committee.

The Crown Office and Procurator Fiscal Service (COPFS) said there are persistent barriers to prosecution, including a distrust of law enforcement agencies by vulnerable teenage girls who have been groomed for sex with cigarettes and alcohol and may not realise they are being exploited.

Mr Graham, Police Scotland's head of major crime prevention and public protection, said: "This week we issued guidance for all our officers and staff to ensure a consistency of response to ­children who may be vulnerable to child sexual exploitation, and to ensure we remain focused on pursuing those who commit offences.

"Through our action plan, our aim is to improve our work in prevention, our training for our police officers and staff, and our work with partners.

"A key part of our plan is the development of a national child abuse investigation unit which will lead and coordinate complex inquiries, develop good practice through making the maximum use of our specialist investigation skills and by improving our links with the third sector and local authorities … improve our intelligence networks to proactively identify such cases."

Some 283 people have been charged over online activity since April 1 last year.

Mr Graham added: "Across the globe the volume of offending through all forms of online activity, whether possession of indecent images of children, online grooming with intent to committing further sexual offences or the exchange of indecent images amongst groups, is escalating due to increased access to mobile devices, improved download technologies and the development of sophisticated software to conceal activity.

"All law-enforcement agencies recognise the challenge this presents but the solution will not be offered by one agency alone, but by working together across the justice sector, across the voluntary sector and with local authorities."

COPFS chief executive Catherine Dyer said recent cases had highlighted that a number of victims of CSE are teenage girls who have lived or are living in care, with complex needs and concerns.

She added: "They can willingly associate with older males who offer cigarettes, alcohol and a night away from their residential home. Many of these teenage ­children do not realise that they are victims of exploitation and even when they commence engagement with the Criminal Justice system they remain extremely vulnerable and distrustful of all agencies.

"This makes detection and subsequent engagement in the investigation and prosecution challenging. These barriers will not deter prosecutors."

Mr Graham has also called for a shake-up of court orders imposed on people who are suspected of committing sexual offences against children but have not been convicted of any crime.

Only 31 Risk of Sexual Harm Orders, which can be applied for by police and granted by a sheriff, have been granted since they were introduced in 2005. Mr Graham said the bar for imposing them should be significantly lowered.