The number of illegal border crossings was relatively low in early 2016 due to mass migrations, when thousands of migrants transited Slovenia heading further north.

The trend started to change when the Balkan route was closed the same year in March, Slovenian police said.

Illegal migrations therefore started to rise in the second half of last year, then dropped in January this year and rose again in February. Police attributed the trend to better weather along the migration route.

Statistics for the entire year 2016 shows that police discovered a total of 1,148 people who crossed into Slovenia illegally, up 142% from 2015.

However, this figure does not include the migrants who entered Slovenia as part of the mass migration wave.

While citizens of Albania and Syria dominated illegal border crossings in 2015, a surge in the number of Afghan and Pakistani nationalas was recorded last year.

Apart from the general rise in the number of undocumented migrants in the first four months of this year, police also recorded a rise in attempts to cross the Slovenian border illegally after the EU introduced tighter controls on the bloc's external borders.

However, the majority of foreigners entering Slovenian since this measure was introduced on 7 April came from Italy, which is in the EU's passport-free zone.

Yet a rise in the number of illegal crossings was also recorded on the external border, according to the police statistics.

On the basis of relevant treaties, Slovenian police returned 182 undocumented migrants to foreign authorities until the end of March, of whom 73% to Croatia.

The majority of those sent to Croatia were Albanian nationals.

Foreign authorities, meanwhile, sent back to Slovenia 83 illegal migrants this year, of whom ten were Slovenians.