Girls are threatened and isolated from their families

A working group is being set up to examine "internal trafficking" of girls in their teens or younger.

In some cases, girls as young as 10 are believed to have been groomed by youths pretending to be boyfriends. They are passed on and end up in prostitution.

Campaigners said the authorities had been slow to react to the problem.

In a report seen by the BBC, the Home Office recommends that "the newly formed UK Internal Trafficking Group will seek to define the extent and nature of this phenomenon".

It can happen to any child from any family

Hilary Willmer, Coalition for the Removal of Pimping

A victim's story A parent's story

Home Office Minister Vernon Coaker confirmed it had commissioned work to examine internal trafficking.

He said a film was also being made to be shown in schools to warn children of the dangers.

"There's work going on with prosecuting authorities to make sure they're aware of this issue and understand it and then there's work going on in communities to make sure that people are aware of this as a potential problem," he said.

"We also want to have services that protect and support victims as well."

Threats and beatings

The BBC has learned that internal trafficking follows a typical pattern in which a girl aged about 12 is approached and won over by a good-looking, well-dressed teenage boy.

He gives her jewellery, mobile phones and later drink or drugs, and pretends to be her boyfriend.

"Emma" told the BBC she was groomed by a teenage boy

Once under his spell, the girl is turned against her parents and persuaded to have sex with her boyfriend's older "uncles" or "friends" to pay him back for the money he has spent on her.

Gradually, she finds herself spending all her time with the older men who force her, often with violence, to work as a prostitute.

Meanwhile, her original "boyfriend" is out targeting another young girl.

One victim Emma, which is not her real name, was targeted when she was 13.

"In schools we're always warned about a man in a white van, but we're never warned that someone nearly your own age could be targeting you to groom you for prostitution," she said.

Emma was too terrified to ask for help.

"They've threatened to rape my mum and make me watch," she said.

"Firebomb my house. Shoot me, shoot my family. They've threatened to do all sorts of things."

Parents 'bewildered'

Hilary Willmer, from the Coalition for the Removal of Pimping (Crop), said she had seen dozens of cases of internal trafficking.

Ms Willmer said: "It can happen to any child from any family. The men, the gangs have all the experience. The children, the families and the parents are bewildered, don't know what's happening."

She welcomed the Home Office action, but said part of the problem was the law.

The whole issue with trafficking is that it's a secret, covert crime and there's a great deal of control placed over the victims

Nick Kinsella

UK Human Trafficking Centre

Once older than 13, a girl may be asked to give evidence in court against an attacker.

"In practice, unless the primary victim is prepared to give evidence then it's very difficult to make charges stick," Ms Willmer said.

"The men know this, so they often wait until the girls are 13 before actually having sex with them."

North Yorkshire Chief Constable Grahame Maxwell said many forces were aware of this problem and officers were now trying to piece together the national picture.

He said: "It is a very difficult crime to detect. We are talking about people who don't want to talk about things in the open.

"When they actually find out the extent to which the exploitation has been carried out on them, how much they have been abused, how much they've been forced to have sexual partners, it's a very difficult thing to comes to terms with."

The UK Human Trafficking Centre (UKHTC) in Sheffield recently appointed a dedicated detective sergeant to work on internal trafficking cases.

Nick Kinsella, head of the UKHTC, said the scale of the problem was unclear.

"The whole issue with trafficking is that it's a secret, covert crime and there's a great deal of control placed over the victims and so that's always difficult to break down irrespective of the age," he said.