Four suspects have appeared in court in Hungary in connection with the deaths of 71 migrants whose bodies were found in a lorry in Austria.
The three Bulgarians and an Afghan, who were arrested in Hungary, were remanded in custody until 29 September. Austria is expected to seek their extradition.
The victims - 59 men, eight women and four children - were found in the abandoned vehicle on Thursday.
Officials said they had probably died of suffocation two days earlier.
The handcuffed suspects were brought to the courthouse in the central Hungarian city of Kecskemet in a convoy of black police vehicles.
They face charges of aggravated human smuggling.
Hungarian law allows suspects to be held for 72 hours before they are either formally charged or released but the prosecutor asked for that period to be prolonged because of the seriousness of the case.
After the hearing, which was closed to the public, head judge Ferenc Bicskei told reporters: "The period of preliminary detention of the four suspects has been extended to September 29."
He said the suspects had appealed against the court decision, saying they had not committed any crimes.
The lorry, which had Hungarian number plates and had travelled from Kecskemet, was found on the side of a main road near the Hungarian border.
Police were alerted when a road worker saw liquid seeping from the vehicle and the badly decomposing bodies were found inside. The victims are thought to be mainly Syrians.
Police suspect the vehicle found its way there as part of a Bulgarian-Hungarian human smuggling network.
So far this month more than 40,000 asylum seekers, the majority of them Syrian, have arrived in Hungary from the Balkans.
Many fall prey to smugglers who wait near the refugee camps, offering to take them at a high price on to western Europe, the BBC's Nick Thorpe in Hungary says.
'Crisis of solidarity'
The gruesome lorry discovery and other tragedies prompted UN Secretary-General Ban Ki-moon to call on Friday for more concerted action to alleviate Europe's migrant crisis.
Mr Ban called for a "collective political response" to avert "a crisis of solidarity".
He called on states involved to "expand safe and legal channels of migration".
On the same day the lorry was found, it emerged that some 200 migrants were feared dead after two boats sank off Libya.
Austrian Foreign Minister Sebastian Kurz told the BBC that the refugee crisis was "the main challenge for the European Union at the moment".
"If we don't find a European solution to the refugee crisis there is a danger that more and more countries try to solve the crisis on their own by building a fence, like Hungary does for example," he said.
Tens of thousands of migrants from conflict-hit states in the Middle East and Africa have been trying to make their way to Europe in recent months.
A record number of 107,500 migrants crossed the EU's borders last month.
The UNHCR says more than 2,500 people have died trying to reach Europe so far in 2015, not including Thursday's deaths.
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