While the eyes of Europe are mostly focused on Brexit, the results of the UK elections and the negotiations at COP25 in Madrid, the Balkan states are again facing a renewed increase in migrants.

A surge in those wanting a better life heading to the West has affected countries from Greece to Hungary and Slovenia. Just in the past month, Hungary has recorded a three-fold increase in illegal border crossings by migrants. All of them come from Serbia, a key country on the migrants' Balkans transit route. 

Hungarian police have discovered two makeshift tunnels dug under its border fence with Serbia. They say migrants were using the tunnels to cross illegally into Hungary. 

At one of Belgrade parks next to the central bus station, dozens of migrants are hanging out at any time of the day, even in this cold December.

There we met Adem, who came from Syria. He complains that he had to pay five thousand euros ($5,500) to the smugglers to take him from Turkey, through Greece, North Macedonia and Kosovo to Serbia.

The route is increasingly attractive to migrants. They are crossing from Serbia's breakaway province of Kosovo to catch local transportation, mostly in the vicinity of the small town of Merdare. From there, the majority go to the northern Serbian city of Subotica at the border with Hungary.

Currently, there are 60 migrants in the state-run One Stop Center camp in Subotica. "In the last month, it is notable that there is an increased number of migrants in illegal camps in Subotica and around." Nikola Sakan, the camp's shift leader, told us.

Migrants in this center are awaiting their turn to legally cross into Hungary.

But Hungary is only letting in one person per working day. The rest are trying to find alternative ways across the border. Security cameras filmed many attempting to scale the border fence. The migrants' desire to reach a better life in the West is overcoming fear and a four-meter-high barbed wire fence.

The number of illegal crossings at the border between Serbia and Hungary has grown steeply in the past few weeks and is unlikely to go down any time soon as all the countries along the Balkan route are reporting the same substantial increase.