VIENNA (AFP) - A human trafficker who crammed 42 migrants into just 6 sq m in the back of a lorry was sentenced to three years in jail in Austria on Tuesday.

"It's not difficult to imagine what it was like with 42 people squashed into 6 sq m," presiding judge Xenia Krapfenbauer said, calling it an "atrocious case of trafficking".

The Romanian defendant, 37, said that he did not know how many people were inside and that he had been paid €1,500 (S$2,400) to drive the lorry.

By the time Austrian police stopped the vehicle in July near Vienna, the migrants had been locked up for seven hours non-stop, with temperatures outside more than 30 deg C.

The migrants from Syria, Iraq and Afghanistan did "thank God" have air, Krapfenbauer said at the trial, in Korneuburg in eastern Austria.

Seventy-one migrants in another lorry found abandoned in Austria in August were not so lucky, suffocating in a case that German Chancellor Angela Merkel called a "warning" to Europe.

Austria is a major transit point for migrants entering from Hungary, on their way to Germany and elsewhere.

Since the August tragedy, Austrian police have stepped up checks for traffickers.