Criminal gangs exploited Europe's refugee crisis last year and made up to £4 billion, according to the European Union's law enforcement agency.
Europol said human traffickers have created a money-spinning industry fuelled by a "seismic" development in the trade in Europe.
Europol's director Rob Wainwright told the Independent on Sunday that the figures were established through debriefings with 1,500 asylum-seekers, refugees and economic migrants which showed that 90% had paid a criminal gang to reach Europe.
We also know that, on average, each migrant is paying between 3,000 and 6,000 dollars to a criminal facilitator for their journey. So you do the simple math and you're up to a turnover in 2015 of between three and six billion dollars. They are big figures. It's running in to billions of dollars made by criminal networks in one year alone in Europe.
Europol identified 10,700 suspects last year from networks spanning from sub-Saharan Africa to Scandinavia.
The scale of the crisis means that smugglers, many of whom may also be involved in the drug trade, have found a new lucrative supply of victims and governments and law enforcement need to toughen up, according to Mr Wainwright.
He said: "We're going to have to up our game in terms of dismantling this criminal infrastructure in a more successful way than we have done in the past."