Brussels - Illegal immigration to the European Union dropped last year to an estimated 150,000 people - the lowest level in five years - the bloc's border agency announced on Friday.

Illegal crossings drop

Migration is a politically sensitive topic across the EU, which experienced a dramatic influx of more than 1 million people in 2015-16. Officials in Brussels fear the issue could galvanize eurosceptics ahead of European Parliament elections in May.

The number of illegal crossings at external EU borders registered last year fell by a quarter compared to 2017 and was 92 per cent below the peak of the migration crisis in 2015, according to the EU Border and Coastguard Agency, also known as Frontex.

The preliminary data reflects the number of detected border crossings, without taking into account the fact that the same person may try to enter several times at different locations.

The drop was due to a "dramatic fall" in the number of people crossing the Mediterranean Sea to Italy, Frontex said in a press release. The number of detections on this route fell by 80 per cent last year, to around 23,000 people.

Departures from Libya, which had been a key staging post for migrants heading for Europe, dropped by 87 per cent compared to 2017.

Migration is a key issue in the EU

However, the number of people reaching Spain via the Mediterranean doubled for the second year in a row to 57,000, making it the "most active migratory route into Europe" for the first time since Frontex began collecting data, the agency said.

Morocco was the main departure point for those heading to Spain, with most migrants on this route coming from sub-Saharan Africa.

In the Eastern Mediterranean, numbers also rose, reaching 56,000 migrants in 2018, according to Frontex. This was attributed to a high number of migrants crossing the land border from Turkey to Greece, as well as a more than doubling of arrivals registered in Cyprus.

Most of those taking the sea route were from Afghanistan, Syria and Iraq, while those reaching Greece by land were mainly Turkish nationals. Eighteen per cent of all illegal arrivals were women, while almost one in five claimed to be under the age of 18, Frontex found.

Migration was a key issue fuelling anti-EU sentiment ahead of Britain's Brexit referendum, while it has also been seized upon by populist parties and mainstream politicians in many countries across the EU.