Study: Migrant-smuggling worth up to $6 billion in 2015

A migrant mops the floor inside a former terminal building at the old international airport, which is used as a shelter for over 3,500 refugees and migrants, in southern Athens, Monday, May 16, 2016. A United Nations envoy for human rights has criticized the European Union's response to the refugee crisis, for showing a "lack of vision," operating under legal ambiguity, and backing the detention of newly-arrived migrants - including children - in Greece. (AP Photo/Thanassis Stavrakis) (The Associated Press)

A five-month-old Syrian baby sleeps inside a tent at a makeshift refugee camp of the northern Greek border point of Idomeni, on Monday, May 16, 2016. Thousands of stranded refugees and migrants have camped in Idomeni for months after the border was closed. (AP Photo/Petros Giannakouris) (The Associated Press)

International law enforcement agencies say smuggling networks cashing in on the huge flow of migrants into Europe had an estimated turnover last year of up to $6 billion.

The agencies say that the number of people trying to reach the European Union is expected to increase, with some 800,000 waiting in Libya to cross the Mediterranean. More than 1.2 million people applied for asylum in the EU last year.

A summary published Tuesday of a joint Europol and Interpol report also warns "there is an increased risk that foreign terrorist fighters may use migratory flows" to sneak into Europe. It notes that two extremists involved in the deadly rampage in Paris on Nov. 13 last year entered the EU through Greece as part of the influx of migrants from Syria.