It comes as the European Union scrambles to find a solution to the continuing mass migration across the continent.
The issue has also highlighted rising tensions between EU members as they disagree on how to tackle the influx.
Officials in Greece say at least 12 Syrians have drowned after their boats sank in Turkish waters as they tried to get to Greece.
The coastguard says two boats sank after setting off from Turkey’s Bodrum Peninsula for the Greek island of Kos.
The dead included a toddler whose lifeless image has been circulated online.
The child can be seen lying face down in the sand on a Turkish tourist beach as an official stands over him.
Meanwhile, police in Austria say they have rescued 24 Afghans locked in a van outside the capital Vienna.
Spokesman Thomas Keiblinger has described the conditions inside the van as awful.
“The police came across a terrible situation. The scene there was really awful. People were sitting or standing on top of each other and had no chance of opening the door themselves from inside. The doors were welded shut. The windows had bars over them. These people were not able to free themselves.”
It comes just days after 71 people were found dead in the back of an abandoned truck.
In neighbouring Hungary, it has been another day of tense scenes after scuffles broke out outside Budapest’s main international train station.
More than 2,000 migrants faced police in the Hungarian capital, with many chanting “Freedom!” and carrying banners.
One Syrian man has described the situation at the train station.
“Nobody knows what we have to do, because I stay here for three days and bought a ticket and pay all my money to buy the ticket and I have just to wait here, because I don’t have entrance to (the station). Even I asked the police, asked the journalists, nobody knows what we have to do.”
It was the largest stand-off in a number of tense encounters following Hungary’s decision on Tuesday to prevent migrants getting on trains to Germany.
A government spokesman, Zoltan Kovacs, has defended that decision, saying no-one will be allowed to travel without valid documents.
“The European Union, including Hungary, should regain its ability to differentiate between refugees proper and economic migrants. Obviously, it’s in the best interests of those arriving, actually, that they have papers and we would be able to establish whether they are coming from Syria or they are coming from other war zones or they are coming there with a different intent — that is, they are economic migrants.”
Germany, meanwhile, has begun accepting asylum claims from Syrians regardless of where they entered the European Union.
That comes despite the bloc’s rules stating migrants must be sent back to the country where they entered.
Germany’s decision has caused confusion for its neighbours, which have alternated between letting migrants through and blocking them.
Germany says it expects about 800-thousand people to file for asylum this year, four times last year’s level.
It has called for a fair distribution of refugees across the EU.
But Britain’s Prime Minister, David Cameron, says he does not think taking in more people is the solution.
“We have taken a number of genuine asylum seekers from Syrian refugee camps, and we keep that under review, but we think the most important thing is to try to bring peace and stability to that part of the world. I don’t think there is an answer that can be achieved simply by taking more and more refugees.”
Rights groups have criticised authorities in the Czech Republic for marking the hands of refugees there with numbers after detaining them on a train.
The measure has triggered memories of Nazi Germany’s practice of marking the arms of concentration-camp prisoners with numbers.
Czech police have used markers to write numbers on the hands of 214 refugees, mostly Syrians, detained at a south-eastern border crossing on trains from Austria and Hungary.
The country’s Interior Ministry has defended the move, saying it was introduced because of the increasing number of children among the refugees.
Elsewhere, Phillippe Douste-Blazy, a former French foreign minister now United Nations under-secretary general, has been visiting the Italian island of Lampedusa.
He has witnessed the rescue of migrants and refugees there.
Mr Douste-Blazy describes the harrowing scenes and the conditions in which people are arriving as a tragedy.
“I think that we don’t speak about that. It is a human tragedy. We have to come back to the Second World War to see these kinds of atrocities. First of all, it is human beings. This is not like immigration policy, the flow of migrants, no. It is human beings.”