Terror groups like ISIS are recruiting unaccompanied child refugees by paying for them to get into Europe.
A report from counter-extremism firm the Quilliam Foundation also warned hundreds of under-18s have gone missing in the UK since migrating.
The youngsters passage to Europe and the UK is being funded by the terror groups, who hand over cash to human smugglers to get them over the border having radicalised them at some stage along the way.
Terrorists are also actively recruiting in refugee camps and a new government strategy isnt expected to address the issues until May.
Militants give out food to the children and attempt to buy their allegiance by paying for the first leg of their journey to Europe.
Children and young people who are indoctrinated and recruited by IS are an important resource, the report says.
Having gained entry to countries in Europe, many children vanish from the care system.
This is understood to be over fears they will not be granted asylum, while others are abducted, trafficked further or sexually exploited, the report said.
The foundations report says extremists may attempt to infiltrate refugee groups and radicalise young minds at any stage of the trip.
Figures from 2015 show 340 children went missing between January and September and that 132 of those remained unaccounted for at the end of the year.
The governments answer to this is expected to include measures to increase the amount of available foster placements and supported accommodation.
Lily Caprani, Unicef UK deputy executive director, said: Currently, too many children with a legal right be in the UK are forced into the hands of criminal traffickers and smugglers because no system is in place to get them to safety.
We need to ensure that children in danger are helped by the law, cared for and educated, and not pulled into a new horror by the lawless.
This shows why it is so urgent for our Government to step up efforts to get unaccompanied children out of dangerous camps and into homes waiting for them in the UK.
Rosalind Ereira from Solidarity with Refugees said: Among the most eye-opening points in this report is the fact that while most of us understand that our failure to provide safe passage to refugees endangers refugee lives, we might not understand that it also creates a threat to our own national security.
Money paid by refugees to smugglers not only helps to fund Islamic State activities, but refugees are signed up to support IS in exchange for their travel.
Where we fail to offer security to refugees, we leave the door open for radicalisation.
We need to understand that the provision of safe and legal routes for refugees is in the best interests of all of us.
Refugees making their way to Europe via the Mediterranean may have to pay smugglers up to $560 for passage towards the coast.
ISIS, capitalising on this route, offer free passage to those willing to join the terror group and the militants are also able to provide a degree of security.
The report says: The financial lure is ever-present on the refugee journey – to those reaching the Mediterranean coast, ISIS offer potential recruits up to $1,000 to join the organisation.