More than 70 people found dead in Austria lorry

Austrian officials now say more than 70 bodies, thought to be asylum seekers, were in an abandoned lorry found on a motorway.

They originally estimated that between 20 to 50 people died in the vehicle, found near the Hungarian border.

The partly-decomposed bodies were piled on top of each other in a cargo container in the vehicle, parked off the highway in Burgenland state.

The shocking discovery cast a shadow over talks in Vienna, where Europe's leaders had gathered on Thursday to discuss the mounting refugee crisis on the continent.

Working in collaboration with Hungarian authorities, Austrian police have launched a cross-border hunt for the missing driver, believed to be Romanian.

The local police chief said it appeared those in the vehicle had been dead for one and a half to two days.

The victims were probably already dead when the vehicle crossed into Austria from Hungary, authorities said.

The vehicle was towed to a customs building with refrigeration facilities in Nickelsdorf on Thursday.

Forensic teams worked through the night to examine the bodies.

"We were all shaken by the horrible news that up to 50 people died... these were people coming to seek safety," German Chancellor Angela Merkel said on Thursday, prior to the new toll being released. 

"This is a warning to work to resolve this problem and show solidarity."

The conference held a minute of silence to commemorate the dead.

This year has seen record numbers of people trying to reach the EU by sea and land as they flee conflicts in Africa, Asia and the Middle East.

In Austria, the number of asylum requests rose above 28,300 between January and June alone - as many as for the whole of 2014 - and officials expect the total to reach 80,000 this year.

The Western Balkans conference was called to find a common European answer to the migrant influx that is overwhelming some countries while leaving others relatively unaffected.