The government must improve support for children who are trafficked into the UK, where care is only available on an ad hoc basis, the charity Unicef says.
Children trafficked in to the UK can end up in prostitution
Each year 1.2m children are trafficked globally for exploitation in the sex industry, as servants or in sweatshops.
Unicef is calling for victims to be given renewable residence permits so they can remain in the UK to recover.
Home Office Minister Vernon Coaker said the government was "committed" to helping to protect vulnerable children.
The government said earlier this year that 330 child victims of trafficking had been identified over an 18-month period.
Unicef said the government must put children's rights at the centre of its policies to safeguard victims.
The study was carried out by Unicef and children's rights organisation Ecpat (End Child Prostitution, Child Pornography and the Trafficking of Children for Sexual Purposes).
And it recommends that the victims should be given renewable residence permits to ensure children can remain in the UK to safely and securely recover from being trafficked.
Currently the government has discretionary powers to decide if a child can stay in the UK. Unicef said this should be changed.
The report said: "A renewable residence permit would secure a legal status for children who had been trafficked and would acknowledge the extent of the human rights abuse and provide the necessary environment in which a child could begin to make a physical and mental recovery.
"It should meet victims' needs and should not be granted in exchange for co-operation with the law-enforcement authorities."
It also states data from across the country must be collected and analysed to reveal the true scale of the problem, and that the results should be reported annually to Parliament.
Responding to the report, Mr Coaker outlined government plans already announced to protect trafficking victims, including the UK Action Plan on Tackling Human Trafficking and the UK Human Trafficking Centre.
"A huge amount of work has been done.
"But there is more to do and we will work with all agencies and colleagues in this field to make sure more progress is made," he said.