The Hungary-Serbia border has been facing great pressure in Europe's largest ever migrant crisis. Hundreds of thousands of people have been arriving at the EU's southern and eastern edges and are trying to make their way to the richer countries further north and west.

This park in central Belgrade used to be a refugee camp. But now it has become a gathering area for illegal immigrants and people-smugglers. The only aim of these people is to cross the border between Serbia and Hungary to enter the European Union. Most of the refugees have spent all they have before arriving at the border.

To stem the influx of refugees, Hungary has adopted a series of strict measures since June last year.

Barriers on the journey include a four-metre high fence along the country's 177 kilometer border with Serbia, 2100 police patrolling the area...and a restricted number of asylum applications -- just 20 people can be approved a day.

Despite that, one or two hundred people wait at the Serbian border customs every day just to get their application approved. Many have stayed there for over a week hungry and desperate.

"We don't have chance, so we need to change our way. We're going to find illegal way," said Afghan refugee Ali.

Some of the refugees who chose illegal means managed to reach western or northern Europe - but some were sent back to Serbia, and some put into jail.