We know that when these children are sent back to their home country they can be left in desperate circumstances.
Academics at Royal Holloway University claim a lack of understanding about child victims' backgrounds can leave them vulnerable to further exploitation when they are deported.
The comments come as Human Trafficking Awareness Day, originally launched by US President, Barack Obama, is marked in countries across the world.
The Government has published the Modern Slavery Bill, which contains new laws that will see human traffickers given maximum life sentences in jail.
But experts from Royal Holloway University, who have been studying the experiences of unaccompanied and separated migrant children in the UK, say more needs to be done for young victims.
Anna Gupta, from the Department of Social Work at Royal Holloway University, 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."
The most recent figures gathered by the UK Human Traffic Centre (UKHTC) show that 549 minors were recorded as potential victims of trafficking to the UK in 2012 - almost a quarter of all those trafficked into this country during that year.
This was only a proportion of the total amount of victims, as it is not compulsory to report them all.
Almost 57 per cent - 310 - were girls. The four countries from which the most children originated were Vietnam, with 103 children, Nigeria, 78, Slovakia, 43 and Romania, 39.
There were also 38 child victims who originated from the UK. Of the 549 victims, 28 per cent were trafficked for sexual exploitation, according to the UKHTC figures.
Ms Gupta said many young victims go missing in Britain in order to avoid deportation and also face risks as undocumented migrants.
The group urged the Government to put children's interests at the heart of its policies to make sure they do not disappear following their initial care in the UK and then face being 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."
Mr Brokenshire said the Government was improving the way victims are identified and supported, and working to prevent people from becoming victims by disrupting, convicting and jailing the criminals involved.
He added: "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."