Up to 300 children are being trafficked into the UK each year and forced into the sex trade, the criminal underworld and slavery with the numbers rising by 25% in the past year.
Statistics from the Inter-Departmental Ministerial Group on human trafficking reveal the number of adults and children trafficked into the UK overall rose by 33% compared to last year.
It found that 946 potential victims of human trafficking, including 234 children, were referred to the National Referral Mechanism (NRM) in 2011 - up from 710 referrals in 2010.
According to estimates from the Child Exploitation and Online Protection Centre 300 children are trafficked into Britain every year.
The report also warned the UK has recently had its first organ harvesting cases, with one involving the planned sale of a victim's kidneys.
In response to the report Barnardo's has called for "urgent action" to protect child victims of trafficking.
The NRM was set up in 2009 as a framework for identifying victims of human trafficking and ensuring they receive the appropriate help.
Their stories include those such as Maria, who was sold by her sister age 13 and taken to Italy, before she eventually ended up in London.
The teenager, from Eastern European, worked as a prostitute, seeing 65 to 70 customers a day.
The report comes as the police carried out raids access the capital, where more than 100 cases of trafficking are dealt with per year.
According to the Inter-Departmental Ministerial Group on human trafficking organised criminal gangs within countries including China, Nigeria, Vietnam, Slovakia and Romania now pose the greatest threat to the UK, where they exploit their victims for sex, labour and domestic slavery.
Barnardo’s chief executive Anne Marie Carrie said: “Policing of child trafficking is improving but it is still very patchy.
"We work with children who have been trafficked into the country and around the country for sex.
"Right now candidates are canvassing for election to be Police and Crime Commissioners and Barnardo’s is calling on them to put child sexual exploitation at the top of their agenda with our Cut them free campaign.
“Urgent action is needed to protect the hundreds of young girls and boys who are being trafficked, abused, raped and exploited for sex.
“We can all do more to protect the children and young people in our lives and in our communities from this increasingly organised and vile abuse.”
The Met police's Detective Insp Kevin Hyland has said the "vast majority" of victims think they're coming to a better life in the UK.
In response to the warnings, immigration minister said Mark Harper told BBC's 5 Live the report would "increase the awareness of what's going on."
"We're doing a better job of cracking down people involved in the vile trade, which is effectively modern-day slavery," he said.