The Government is failing to put the welfare of child trafficking victims above concerns about immigration control, a group of experts has warned.
A team of academics at Royal Holloway University has warned UK authorities' lack of understanding about child victims' backgrounds can leave them vulnerable to further exploitation, either in the UK or abroad if they are deported to their home country.
The comments come as Human Trafficking Awareness Day, originally launched by President Barack Obama, is marked in the US and other countries across the world.
The Government has published t he Modern Slavery Bill, which contains new laws that will see human traffickers given maximum life sentences in jail.
Bringing together expertise from Royal Holloway's social work, geography and media arts departments, a group of academics have been studying the experiences of unaccompanied and separated migrant children in the UK.
Anna Gupta, from the Department of Social Work at Royal Holloway University, said not enough is being done to care for child victims.
She said: "Child victims are held against their will and can be forced into a life of sexual abuse, domestic servitude or criminal activity.
"However, if they are identified and rescued, they then have to go through a series of complex and stressful asylum or immigration processes.
"Indeed, some children such as Vietnamese boys trafficked to work in cannabis factories, are often treated as criminals not victims.
"We know that when these children are sent back to their home country they can be left in desperate circumstances and are at risk of exploitation by traffickers once again.
"Many young victims go missing in the UK in order to avoid deportation and also face similar risks as undocumented migrants.
"New measures could include providing a legal guardian for child victims to support them through the duration of their care.
"This would be a critical step towards ensuring that young trafficking victims get the support they need and help ensure their welfare into adulthood."
The Government has been urged by the group to put the interests of children at the heart of its policies, to ensure child victims do not disappear following their initial care in the UK and are then re-trafficked.
Security Minister James Brokenshire said: "Modern slavery is an appalling crime and particularly abhorrent when it involves children. The safety and welfare needs of child victims is paramount.
"All victims, regardless of nationality, are entitled to the same level of protection and support and are assessed against exactly the same criteria. Addressing the needs of the victim and investigating the crime against them are the priorities.
"As well as improving the way victims are identified and supported, we are working to prevent people from becoming victims in the first place by disrupting, convicting and imprisoning the criminals involved.
"The Home Secretary and I have made clear that to end modern slavery we need to tackle the organised criminal gangs behind the majority of it, rather than simply treating it as an immigration problem."