An unprecedented 1.82 million migrants illegally crossed into the EU last year, increasing the security threat across Europe where militants have taken advantage of disjointed border enforcement, border agency Frontex reported Tuesday.
The number of illegal crossings was six times the previous record held in 2014.
Border officials predicted that migrants would continue to flow in masses toward the EU given the proximity of war torn areas and the sustained economic disparity between European states and conflicted nations.
Syrians represented the largest share of arrivals, though the report noted that their exact number is difficult to determine since many other migrants claim to be from Syria in an attempt to speed-up travel.
Afghans marked the second highest proportion while Iraqis made up the third largest nationality crossing into EU member states.
Border officials said there has not been a migration crisis to this degree since World War II.
The trend of irregular migration has also contributed to an increased terrorism threat across Europe, according to the report.
Two of the terrorists in the November Paris attacks used fraudulent Syrian passports to enter the Greek island Leros where authorities registered them under the pretense that they were refugees.
Frontex officials said the attacks "demonstrated that irregular migratory flow could be used by terrorists to enter the EU."
"With no thorough check or penalties in place for those making such false declarations, there is a risk that some persons representing a security threat to the EU may be taking advantage of this situation," the report said.
Border officials said EU member states need to increase screening and registration processes while implementing advanced information sharing measures to strengthen border security.