Young people continue to be smuggled into the UK to be sexually exploited, put to work or forced into marriage, a study has found.
Trafficked children can be forced into sex
Ecpat UK - a group of charities against child exploitation - found 80 children thought to be trafficked were taken into care in the last three years.
But, it said, 48 of them had gone missing and had never been found.
One campaigner said the trafficking was a "contemporary form of slavery". Ecpat is calling for tougher penalties.
It says it wants the battle against child trafficking to come ahead of immigration concerns.
The charity's report is based on studies in the North East, North West and the Midlands.
Children in the study originally came from China, Vietnam, Nigeria, Benin, Togo, Cameroon, Congo, Somalia, Liberia, Eritrea, Burundi, Uganda, Moldova, Russia and Albania.
Christine Beddoe, director of Ecpat UK, said: "Child victims of trafficking are missing out on accessing essential care because of their isolation, their uncertain immigration status and because they have no advocate who can speak on their behalf about their special needs."
She added: "Child trafficking is a contemporary form of slavery, and children must get access to safety, security and proper health care.
"UK immigration control strategies treat these children as illegal migrants first, children second, and this creates a barrier to keeping them safe."
Colette Marshall, UK director of Save the Children, said the report had "important evidence" about child trafficking in the UK.
"Local authorities are working hard to protect these vulnerable children, however, additional resources and guidance are required from the UK government to ensure child trafficking becomes a priority - not for a few front-line childcare workers, but for all professionals that come into contact with these children," she said.