The level of arrivals of irregular immigrants to the EU has dropped to its lowest level since 2013, the bloc's border security agency Frontex said Friday.

At the same time, the number of migrants sent back to their country of origin has risen, the agency's chief, Farbice Leggeri, told a media conference in Brussels.

But a breakdown of the figures for 2019 showed that, while overall arrivals at the EU's external borders had declined 92 percent from the massive spike recorded in 2015, that was due to a big cut in migrants trying to cross from the Mediterranean from North Africa to Italy or Spain.

There were still sustained numbers trying to enter the EU along its eastern rim, through Greece, Bulgaria and Cyprus, where border crossings were 46 percent higher than in 2018, and a similar jump was noted for Croatia and Hungary.

Afghans and Syrians were the biggest groups entering the bloc, Leggeri said, explaining that conflict and political instability were driving the influx. Increasingly adverse conditions for Afghans in Iran and Pakistan were also spurring their movement.

Leggeri noted that returns were at a record level, with 15,850 being sent back, many on commercial flights, which he hailed as "an extremely effective" method.

Germany, Italy, France and Belgium topped the EU countries availing themselves of Frontex's returns operations, with the main countries taking back their nationals being Albania, Tunisia and Georgia.

Leggeri said that Frontex's mission would be significantly beefed up from next year when the agency's first full time uniformed staff of border and coast guard officers would start being deployed.

That corps, recruited from 7,500 applicants over the past three months and soon to be trained up, will supplement national border forces when EU member states in the Schengen zone feel they need help. The Frontex force, to eventually be built up to 10,000 over the next seven years, can also be called on to assist countries outside the EU's borders when requested.

Leggeri stressed however that Frontex will need sufficient funding from the EU's longterm 2021-2027 budget currently the subject of heated negotiations between members states.

Some EU countries are balking at how much more they would have to cough up to cover some of the 84-billion-euro ($93-billion) shortfall over the next seven years to be caused Britain's exit from the bloc.