The people, from Afghanistan, were between 14 and 31 years old and entered the lorry in Serbia, according to the police.

The truck originated in Turkey and was laden with fruit.

The Afghans have been transferred to the authorities, the police said.

The driver of the lorry pulled over near the town of Passau, situated on the Austrian border, after hearing knocking sounds coming from the vehicle.

The migrants said they were having trouble breathing.

The police opened the lorry. They said they believed the driver had not known the migrants were in the vehicle.

If the refrigerated lorry had continued to its destination in Belgium, it could have been life-threatening for the people trapped inside.

Recently, 39 Vietnamese migrants died in a refrigerated lorry in Essex, in south-east England.