White, black and Asian children at risk with abusers using mobiles and web to groom victims, say Barnardo's

The trafficking of British children around UK cities for sexual exploitation is on the increase with some as young as 10 being groomed by predatory abusers, a report reveals today.

The average age of victims of such abuse has fallen from 15 to about 13 in five years, according to the report by Barnardo's, the UK's biggest children's charity.

But victims continue to be missed as telltale signs are overlooked "from the frontline of children's services to the corridors of Whitehall," said Anne Marie Carrie, the charity's new chief executive.

"Wherever we have looked for exploitation, we have found it. But the real tragedy is we believe this is just the tip of the iceberg," she said.

Calling for a minister to be put in charge of the government's response, she said: "Without a minister with overall responsibility the government response is likely to remain inadequate."

The main findings from the report, called Puppet on a String, include:

• Trafficking becoming more common and sexual exploitation more organised.

• Grooming methods becoming more sophisticated as abusers use a range of technology – mobile phones, including texts and picture messages, Bluetooth technology, and the internet – to control and abuse children.

The charity dealt with 1,098 children who had been groomed for sex last year, a 4% increase on the previous year.

A recent focus on the ethnicity of abusers risks putting more children in danger, said Carrie. "I am not going to say that ethnicity is not an issue in some geographical areas, it clearly is. But to think of it as the only determining factor is misleading and dangerous."

The issue has come under the spotlight after cases in Derby, where ringleaders of a gang of Asian men were jailed for grooming girls as young as 12 for sex, and in Rochdale, where nine mainly Asian men were arrested on Tuesday last week on suspicion of grooming a group of white teenage girls.

Carrie warned of the risk of the issue becoming dangerously simplified after comments from the former home secretary Jack Straw, who said some Pakistani men saw white girls as "easy meat".

The charity dealt with white, black and Asian victims, she said – whose voices were being lost. "Profiling and stereotyping is dangerous – we are scared that victims will say: 'I don't fit into that pattern, so I'm not being abused'."

The report identifies many different patterns of abuse, ranging from inappropriate relationships to organised networks of child trafficking.

Of Barnardo's 22 specialist services surveyed for the report, 21 had seen evidence of the trafficking of children through organised networks for sex, often with multiple men.

Among the cases highlighted is Emma, who met her first "boyfriend" when she was 14. In his 30s, he bought her presents, said he loved her, then forced her to have sex with his friends. She was shipped around the country and raped by countless men. "I got taken to flats, I don't know where they were and men would be brought to me. I was never given any names, and I don't remember their faces," she said.

The "inappropriate relationship" usually involved an older abuser with control over a child. Such cases included Sophie, who was 13 when she met her "gorgeous" 18-year-old boyfriend at a cousin's 21st birthday party. After initially treating her well, he isolated her from her family and became violent. When police rescued her, they told her the man was 34, with a criminal record for child abuse. "I said they were lying. I thought I was in love, I thought it was normal," she said.

The "boyfriend" model, sees girls groomed, often by a younger man, who passes her on to older men. In one case an Asian teenager from the north-west described being dragged out of a car by her hair by her "boyfriend", who took her to a hotel room "to have his friends over and do what they wanted to me".

Boys are also vulnerable: a 14-year-old, Tim, was groomed by one man then expected to have sex with many more. "After a while there would be three or four guys all at once. It was horrible and very scary," he said.

Abusers are increasingly using the internet and mobile phone technology to control victims. Teens are being coerced into sending, or posing for, sexually explicit photos which are then used to blackmail and control them, said Carrie. "The abuser then sells the images, and threatens to send the pictures to the girl's parents or school if she does not do x, y and z."

Often abusers target the most vulnerable: children in care, foster homes or from chaotic backgrounds. But children of all backgrounds are at risk, said Carrie.

Penny Nicholls, director of children and young people at The Children's Society, said the Barnardo's findings echoed their experiences. "We join Barnardo's in calling on the government to take urgent action, ensuring a minister has special responsibility for overseeing a countrywide response to combat sexual exploitation."

A Department for Education spokeswoman said: "This is a complex problem and we are determined to tackle it effectively by working collaboratively right across government and with national and local agencies."