A Hungarian court has extended the prison sentences of four human traffickers convicted last year for their roles in a 2015 incident in which 71 migrants suffocated in the back of a refrigerated truck found on a highway in Austria.

According to yesterday's decision by an appeals court in the southern city of Szeged, an Afghan man and two Bulgarian accomplices were sentenced to life in prison without the possibility of parole, while another Bulgarian man able to request his release after 30 years in prison. A year ago, all four had been given 25-year sentences for belonging to a criminal organization and committing multiple crimes, including human smuggling and manslaughter. Ten other defendants, mostly Bulgarians, were given prison terms ranging between four and 12 years.

The victims, from Syria, Iraq and Afghanistan, were among hundreds of thousands of desperate people fleeing war and poverty in the Middle East and elsewhere in 2015, triggering Europe's worst migrant crisis since World War II. Hungary took over the proceedings from Vienna after it emerged that the migrants had suffocated on Hungarian soil.

Hungarian prosecutors said the ring was a professional trafficking network with more than 15 vehicles used to transport refugees trekking up from Greece along the western Balkans to Europe. The Budapest-based gang smuggled more than 1,100 people from Hungary into Austria from February 2015, charging up to 1,500 euros ($1,760) per person. The bodies of 59 men, eight women and four children, including a baby girl, were already in an advanced state of decomposition when they were discovered in an abandoned poultry refrigerator lorry on Aug. 27, 2017.