An eighth case of dioxin contamination has been found on a German poultry farm, this time near Loehnberg in the state of Hesse, the latest in a series of incidents.

Eggs from the farm are being recalled, the federal food warning service has reported.

It follows seven previous discoveries on farms in Lower Saxony and the neighbouring state of North Rhine Westphalia since April.

The cause for the latest outbreaks remains unclear. They follow a more widespread dioxin problem in early 2011 related to feed contamination, that prompted the German authorities to tighten controls.