A farmer has accidentally killed his 3-year-old son with his tractor and trailer in a tragic accident near Lake Constance in Austria, Austrian police said on Friday.

The 50-year-old farmer was driving his tractor through the stable alley of his cattle barn in Höchst near Bregenz, in the state of Vorarlberg – around 15 kilometres from the German border – to distribute feed for the animals.

The child had followed behind on his bicycle without being noticed.

At the end of the barn, the farmer reversed his tractor and the trailer tyre struck the young boy.

Resuscitation attempts were unsuccessful.