Austria, Hungary, and Serbia have called on the European Union to step up efforts to fight human smuggling through the Balkans.
Meeting in Budapest on June 30, the interior ministers of the three countries signed an agreement to send more personnel and technical equipment to joint police patrols on Serbia's borders with Hungary and Macedonia.
Austria is to send 80 police and special cameras to detect migrants on the Serbian borders.
Serbian Interior Minister Nebojsa Stefanovic said Europe was facing a humanitarian crisis.
"It is summer now, but the winter will come soon when we will need [many] more doctors, accommodation, and food," he said.
Earlier on June 30, the European Commission pledged to send financial aid and experts to Hungary to help it cope with a surge in illegal immigration this year.