Germany’s egg industry has been hit by a new dioxin scare just days before Easter.

Inspectors have temporarily closed down a 25,000-hen organic farm in the western state of North Rhine-Westphalia, after eggs were found to contain up to six times the legal limit of polychlorinated biphenyls (PCBs), which are dioxin-like substances.

It is not yet clear how the eggs became contaminated with PCBs. Initial tests on the feed used on the farm were negative, but authorities are now looking to investigate older feed batches. The farm procured its feed from a supplier in Lower Saxony, where local authorities have been alerted.

According to authorities in North Rhine-Westphalia, the farm kept laying hens in four houses – the eggs from two houses were found to contain PCB levels significantly above the legal limit, while eggs from the other two were found to have just slightly elevated PCB levels.

The farm last sold eggs to the public on 7 March, primarily via supermarkets.

Last January, high dioxin levels in German eggs and meats led to thousands of farms being closed down. However, German authorities have said they believe the current scare is likely to be an isolated incident, adding that the eggs were not believed to present any “acute danger” to consumers.