The UN aid agency UNHCR warned on Monday (26 October) the procedure of registering people will slow down the flow of migrants, creating problems during the winter season. Senior UNHCR Coordinator Francesca Bonelli present at the Serbian border crossing with Croatia, said that the agency supports proper registration but that they are not equipped to deal with the bottle necks the process will create.

"We support proper registration process but of course they slow down, it''s an issue if the winter is coming and the shelter facilities are not available, because particularly to spend a night, if this process slow down, it will be a challenge to properly protect many people that are outside, in the cold weather, rain and without any protection," she said.

Thousands of migrants and refugees crossed the border from Serbia into Croatia on Monday, as they made their way northwards across Europe. Croatian police kept the gate open, allowing entry to groups of around 100 people at a time. Bonelli also said the facilities at the border crossing were not adequate to deal with the influx of migrants that have to wait in the cold.

"The queuing time is always a problem. I can see that people are incredibly anxious to pass the border to go ahead, to reach the final destination and when the bottleneck is creating with more people with one thousand, two thousand people waiting, there are security problem, there are conditions very tough for particularly people with specific needs, and this is our worry that we cannot properly support and protect the people that are passing through in a dignified way," she added.

European Union and Balkan leaders meeting in Brussels agreed a 17-point plan to cooperate on managing flows of migrants through the Balkan Peninsula, the European Commission said early on Monday.

Following years of economic crisis, Europe's governments are struggling to cope with an influx of people from countries including Syria. With the route through Hungary now closed, the migrants have been forced to re-route westwards through Croatia and Slovenia.