A FIFTH man suspected of being involved in the deaths of 71 migrants found in a truck in Austria has been detained, Hungarian police have said.

The Bulgarian national was arrested on Saturday evening, police said. A spokesman said they will seek to have him held in custody on suspicion of human trafficking, but gave no further details about him.

On Saturday, a court in the central Hungarian city of Kecskemet, where prosecutors say the truck departed, placed four other suspects under preliminary arrest pending possible indictment in the case.

Three other Bulgarians and an Afghan were arrested on Thursday in southern Hungary, after the truck with the dead migrants was found earlier that day parked along the Budapest-to-Vienna motorway.

Austrian experts are performing post-mortem examinations on the migrant victims – 59 men, eight women and four children.

Austrian police have said the migrants likely suffocated to death. As of Sunday, there was no conclusive information yet on the cause of death, a police spokeswoman said. The process will continue for several days.

The identity of the migrants remains unclear. Police have set up a hotline for people who may have information on who was aboard. Investigators have found a Syrian passport in the truck.

“One can suspect that this was a Syrian group, or (that there were) a few Syrians,” Burgenland province police chief Hans Peter Doskozil said. “But it could be mixed.”

Hungarian police have detained 22 people suspected of human trafficking in several cases over the weekend. They included nine Hungarians, seven Romanians, three Serbians, as well citizens of Austria, Lithuania and Poland. Among the migrants found in the vehicles were 160 Syrians, 21 Iraqis, 20 Afghanis and two from Pakistan.

Romania’s foreign ministry said on Sunday that 26 Romanians had been detained in Hungary recently, suspected of human trafficking. Police in Austria’s Burgenland province, where the truck with the dead migrants was found last week, said on Sunday that they had arrested five suspected smugglers in four separate incidents in the past two nights. The suspects – three Hungarians, a Croat and an Italian – had brought 36 people into Austria.

The Austrian government said that it was stepping up checks near the country’s eastern border starting on Sunday evening, and officials will stop and check large vehicles.

At Budapest’s Keleti train terminal, meanwhile, several hundred migrants protested at the terminal’s main gate, demanding that Hungarian authorities allow them to travel to Germany.

Migrants applying for asylum after crossing over from the southern border with Serbia are registered by authorities and usually sent by train to refugee centres, passing through Budapest.

They are supposed to stay in Hungary until their asylum requests are settled but many, who have avoided being registered, quickly try to go to richer EU countries, especially Germany. lMore than 2,500 migrants have been plucked from the sea in dozens of search and rescue operations off the Greek islands over the weekend.

Coastguard officials said 2,492 people were rescued in 70 operations off the eastern islands of Lesbos, Chios, Samos, Agathonissi, Farmakonissi, Kos and Symi and another 13 people from the water near the port of Chios. lYesterday German Chancellor Angela Merkel said that if Europe was not able to agree to a fair distribution of refugees, the passport-free Schengen zone would be called into question.