Austria, Hungary and Serbia called on the European Union on Tuesday to step up efforts to fight human smuggling through the Balkans and not just focus on southern immigration routes.
Austria has become the biggest target of illegal immigrants and most of them reach the landlocked country through the Balkans, Austrian Interior Minister Johanna Mikl-Leitner said.
"We are at the limits of our ability to bear the burden," she told a joint news conference with her Hungarian and Serbian colleagues.
The three ministers signed a memorandum of understanding to increase cooperation in patrols along Serbia's borders with Hungary and Macedonia and in the fight against human smuggling.
Austria will send 80 police and special cameras to detect migrants on the Serbian borders.
Mikl-Leitner said Austria had to take care of 40,000 migrants who have applied for refugee status and the number could grow to 70,000 this year.
Hungary has received 67,000 such applications so far this year and its shelters are overcrowded, even though most of the migrants there move on to richer EU member states such as Austria and Germany.
Nebojsa Stefanovic, the interior minister of Serbia, which is not an EU member, said his country, still reeling from a refugee wave during the Yugoslav wars in the 1990s, also needed help to face a wave of migrants along its border with Macedonia.
He said Europe was facing a humanitarian crisis.
"It is summer now, but the winter will come soon when we will need much more doctors, accommodation and food," he said.
Earlier on Tuesday, the European Commission offered to help set up temporary centers for the Hungarian government to process asylum requests and eventually return illegal immigrants.
Dimitris Avramopoulos, the EC's senior official on migration pledged nearly 8 million euros in aid and various other measures for Hungary.
Hungary is in the European Union's Schengen visa-free travel zone and thus has become an attractive destination for tens of thousands of migrants entering Europe through the Balkans from the Middle East and Africa.
Hungary, which says it no longer has the means to deal with a sharp increase in people streaming over its border, stands by its plan to build a 175-km (110-mile) fence along the Serbian border to keep out migrants.
On Wednesday, the governments of Serbia and Hungary will hold a joint government meeting in Budapest on migration issues.
As Austria, Hungary and Serbia struggle with their migrant flows, much international attention has been focused on the crisis in the Mediterranean, with tens of thousands of people seeking to reach Italy and Greece on a flotilla of frail boats.
An estimated 2,000 migrants have drowned so far this year trying to make the crossing.