A truck in which up to 50 migrants were found dead, is prepared to be towed away on a motorway near Parndorf, Austria August 27, 2015.[Photo/Agencies]

QUOTAS

"Every week we learn of more deaths and drownings on the Mediterranean route because the boats people are packed on are unseaworthy or overcrowded. Now we are hearing of cases of mass deaths along the land journey. This terrible tragedy shows the unscrupulous business of smugglers who have no regard for human life is extending across the continent," said Melissa Fleming, spokeswoman for the U.N. High Commissioner for Refugees.

European Commissioner Johannes Hahn reiterated that Brussels would propose within weeks a fresh look at the situation.

"We will have another go at quotas. I hope that in the light of the most recent developments now there is a readiness among all the 28 (member states) to agree on this," he said.

German Foreign Minister Frank-Walter Steinmeier, whose country expects 800,000 asylum seekers this year, said a fair distribution of refugees was needed to ensure support in countries taking in the bulk of migrants.

His Austrian counterpart Sebastian Kurz said: "If we are not able to find a quick European solution here, then more and more countries like Hungary and Denmark - who are already doing it - will try to solve this crisis for themselves on their own with individual measures and their own initiatives.

"It won't work and above all it threatens our European idea of having open borders and with that proper security at the EU's outer borders."

Serbian Foreign Minister Ivica Dacic put the onus on EU countries to find a better way to handle the influx of refugees.

"So you have a problem but you are asking us, Serbia, to come up with the action plan for migrants. You should come up with an action plan first."