More than 4,700 farms have been closed in Germany, as a precautionary measure, following an alert over dioxin contamination of animal feed, the agriculture ministry said.
"4,709 farms and exploitations are currently closed," including 4,468 in the state of Lower Saxony, northwest Germany, said the ministry statement summarising the actions of regional authorities.
Until the farms have been checked and found to be clear of contamination of dioxin, which can cause cancer, they will not be allowed to make any deliveries.
State officials applied the ban on deliveries to any businesses involved in the production of the fodder at the centre of the scare, said the agriculture ministry in Berlin.
"This strategy explains the high number of closures," but the bans should be progressively lifted in the coming days once tests had been carried out, the ministry added.
It was in Lower Saxony that 2,500 out of the 3,000 tonnes of contaminated fatty acids at the centre of the alert were delivered in November and December, where they were used as animal fodder.
The firm Harles und Jentzsch in the northern state of Schleswig-Holstein is alleged to have supplied up to 3,000 tonnes of contaminated fatty acids meant only for industrial usage to around 25 animal feed makers.
Nine samples out of the 20 that were analysed showed dioxin levels higher, or much higher than legal, the Schleswig-Holstein ministry said.
The fat is therefore not allowed for consumption, it added.
The German government said earlier that up to 150,000 tonnes of feed were feared to have been contaminated.
The dioxin scare had already resulted in a halt in production at about 1,200 chicken, turkey and pig farms, most of them in northern Germany.
There are around 375,000 farms in Germany.
A dioxin level that exceeded legal levels in eggs was found in late December.
The scare started in two German states, eventually spreading to 11 others.
But only eight of them, including Lower Saxony, were hit by Thursday's closures.
Worst hit after Lower Saxony were the western state of North Rhine/Westphalia where 152 farms were closed; 52 farms in Schleswig-Holstein and 27 in the eastern state of Saxony-Anhalt.
German authorities on Wednesday informed the EU's executive Commission and business partners that 136,000 eggs, or nine tonnes of the product, from contaminated German farms had been exported to the Netherlands.
The European Commission said Thursday the hunt for potentially dioxin-tainted eggs had also turned to Britain.
Dioxin, a by-product of burning rubbish and industrial activities, can cause miscarriages and other health problems in humans, including cancer.