Footage has emerged of migrants being thrown bags of food at a Hungarian camp near the border with Serbia.
An Austrian woman who filmed the video said the migrants were being treated like “animals” and called for European states to open their borders.
It comes as Central European states, Germany and Luxembourg are due to meet over the migrant crisis.
Germany is pushing a quota system that would oblige EU states to take fixed numbers of new arrivals.
The European Commission wants 120,000 additional asylum seekers a year to be shared out between 28 members – a sharp increase from the previous proposal of 40,000.
But the Czech Republic, Hungary, Poland and Slovakia have rejected the proposals.
In recent weeks, tens of thousands of migrants have been desperately trying to flee conflicts in countries such as Syria and Libya.
Many of them travel through Hungary to Germany, Austria and Sweden – wealthier EU nations with more liberal asylum laws.
Hungary in particular has become a key point on the journey north for the migrants, with more than 150,000 people arriving this year.
The footage from Hungary comes from a camp at Roszke, one of the bottlenecks at which large numbers of migrants heading north and west have built up.
It was filmed by Michaela Spritzendorfer, the wife of an Austrian Green party politician who was delivering aid to the camp, and Klaus Kufner, a journalist and activist.
“These people have been on a terrible tour for three months,” Ms Spritzendorfer told the BBC.
“Most of them have been across the sea now and on the boat and through the forest and they’ve gone through terrible things and we, as Europe, we keep them there in camps like animals. It’s really a responsibility of European politicians to open the borders now.”
The lack of support for migrants in Hungary has drawn criticism from activists. Peter Bouckaert, emergency director at Human Rights watch, described the situation at Roszke as “inhumane”.
The Central European nations – the so-called Visegrad-four – have all rejected the proposed compulsory quotas, despite the fact that each of them would take in far fewer refugees than Germany if the EU backs the proposals.
Ahead of the Prague meeting, the Czech Foreign Ministry said it was aimed at improving “better mutual understanding among EU member states… [in light of] some differing views”.
On Wednesday, the Hungarian army started military exercises to prepare for a possible future role in guarding the border and stemming the flow of people – a move criticised by human rights groups.
A new razor-wire barrier is also being built along the country’s border with Serbia.
The authorities in Hungary have been told to expect 40,000 more migrants by next week.
A note on terminology: The BBC uses the term migrant to refer to all people on the move who have yet to complete the legal process of claiming asylum. This group includes people fleeing war-torn countries such as Syria, who are likely to be granted refugee status, as well as people who are seeking jobs and better lives, who governments are likely to rule are economic migrants.