Francesco Malavolta, Associated Press
In this photo taken Sunday, April 26, and made available April 28, 2015, a rescue unit, belonging to the Icelandic Coast Guard vessel Tyr deployed by Frontex, takes part in a drill off the Sicilian coast, in the Mediterranean Sea, Sunday. Border agents are so busy dealing with the record number of migrants entering the European Union that they can no longer screen people properly, leaving them to slip deeper into the EU unidentified, Europe's border agency Frontex said Tuesday.

BRUSSELS — Border agents are so busy dealing with the record number of migrants entering the European Union that they can no longer screen people properly, leaving them to slip deeper into the EU unidentified, Europe's border agency Frontex said Tuesday.

In its new migration analysis for 2015, Frontex said that resources are focused on migrants' "immediate care, rather than screening or obtaining information on their basic characteristics such as nationality."

Once rescued, these migrants "continue their journey to other member states," the agency said, and that that not knowing who is traveling within the EU is "a vulnerability."

A record 280,000 illegal border crossings were detected in the EU last year, according to Frontex analysts. More than 170,000 came through the Mediterranean, chiefly from Libya — a 277 percent increase over 2013. Most were from Syria and Eritrea.

While younger men make up the overwhelming majority of people trying to enter Europe without visas, more families had been crossing borders of late.

"Border control authorities need to be prepared to manage flow of vulnerable people, including numerous children," Frontex warned.

EU leaders last week pledged to double the number of ships and aircraft in Frontex's Triton border control operation in the southern Mediterranean. They also decided to triple the operation's budget, back to the levels used to fund Italy's navy search and rescue mission, Mare Nostrum, which was phased out late last year.

Some of the assets for the expanded operation, which include border and migration experts, will not be available for several months, and many are only being offered for a month or two.

Nils Muiznieks, human rights commissioner at the Council of Europe, said Tuesday that those resources "will probably not be sufficient to meet the challenges the EU faces."