A boat full of migrants is seen next to Swedish ship Poseidon during a rescue operation in the sea off the coast of Libya in this still image taken from an August 26, 2015 video.[Photo/Agencies]

SWEEPING NORTH

In Europe, refugees and migrants have swept north through the Balkans in recent days, with thousands of Syrians, Afghans and Pakistanis crossing from Serbia into EU-member Hungary, where authorities said more than 140,000 had been caught entering the country so far this year.

Almost all hope to reach the more affluent countries of northern and western Europe such as Germany and Sweden.

Hungary, which is part of Europe's Schengen passport-free travel zone, is building a high fence along its border with Serbia to confront what it says is a threat to European security, prosperity and identity.

Austrian police had originally put the death toll in the truck found abandoned near the Hungarian border on Thursday at about 50, but later raised the figure to 71.

The refrigerated vehicle was found by an Austrian motorway patrol with fluids from the decomposing bodies seeping from its back door. It had been abandoned on the side of the highway that leads from Hungary to Vienna.

The truck is at a customs building in the village of Nickelsdorf, which has refrigeration facilities and where forensic specialists in white protective suits and yellow rubber boots could be seen wheeling body bags away.

In Hungary, police said 10 Syrian migrants were injured on Friday when a van driven by a Romanian suspected of human trafficking overturned en route for Budapest.

At a Geneva briefing, the UNHCR said that in one incident on Thursday, 51 people suffocated in the hold of a boat and survivors said they had been beaten to force them into the hold and then had to pay money to smugglers just to come out to breathe.

One of the survivors, an Iraqi orthopaedic surgeon, said he had paid 3,000 euros ($3,400) to come up on to the top deck with his wife and two-year-old son.

Last week, 49 people died in another boat's hold after inhaling poisonous fumes, and on Wednesday 21 people are thought to have died after a dinghy with 145 on board got into difficulty, UNHCR spokeswoman Melissa Fleming said.