The European Union's border agency says the number of migrants entering the bloc without authorization continues to drop.

Frontex said Tuesday that it spotted 4,900 "illegal border crossings" in April, a fall of 19% over the previous month.

In all, about 24,200 crossings were detected in the first four months of 2019, 27% down from in 2018.

More than half the unauthorized migrants were detected on Europe's eastern borders. One in four were Afghans, while one in five were citizens of Turkey, a candidate for EU membership.

Just over 200 people crossed the central Mediterranean, once Europe's busiest migrant route.

The EU was plunged into a political crisis in 2015 over how to handle migrant arrivals. Surveys say migration is a key issue in the May 23-26 EU elections.