Interpol has warned that 800,000 migrants are waiting in Libya to try and make the crossing to Europe.
A joint report by the crime fighting organisation, and its European counterpart, Europol, was seized on by Leave campaigners.
Looking ahead to future trends, the document stated: "Overall, an increase in the number of migrants trying to reach the EU is expected. In Libya alone, around 800,000 migrants are waiting to travel to the EU."
The report found that a systematic link between people smuggling and terrorism had not be proven, but there is "increased risk" terrorists may use migratory flows as cover.
Migrants are vulnerable to sexual exploitation in order to pay debts to smugglers, the study said.
"While a systematic link between migrant smuggling and terrorism is not proven, there is an increased risk that foreign terrorist fighters may use migratory flows to (re)enter the EU.
"It is expected that, in 2016, more than 90% of the migrants moving towards the EU will be facilitated by smugglers. Within Europe an increase and change of facilitation services is likely due to the recent closure of the national borders of several European countries.
"Key migratory routes identified as main corridors for migrant smuggling are fluid and influenced by external factors like border controls.
"Migrants who travel to the EU are vulnerable to labour or sexual exploitation as they need to repay their debt to smugglers.
"Migrant smuggling is a multinational business, with suspects originating from more than 100 countries.
"The structure of migrant smuggling networks includes leaders who loosely coordinate activities along a given route, organizers who manage activities locally through personal contacts, and opportunistic low level facilitators," the report states.
Ukip's Steven Woolfe said the probe's findings backed up the security fears of ex-MI6 chief Sir Richard Dearlove who insisted Britain would be safer outside the EU.
"This joint report from Interpol and Europol demonstrates that 800,000 Libyans are queuing up to enter the EU. It is absolutely clear, from Richard Dearlove to Interpol, that we already have thousands of Jihadi terrorists in Europe.
"Libya is awash with trained, skilled and determined Isis terrorists who are bound to be amongst those seeking to enter the EU.
"Intelligence says that it is only a matter of time before another terrorist attack occurs in Europe. The crisis isn't over, it's just continuing and getting worse.
"Unless we vote to leave, we will putting our national security at risk and increasing the likelihood of terrorism on our shores," Mr Woolfe said.
The report reveals that people smugglers made between 5-6 billion US dollars trafficking people into Europe last year.