Up to 3,000 tons of an additive for animal feed contained traces of dioxin, a cancer-causing substance, according to a German Agriculture Ministry briefing paper obtained Wednesday by the German Press Agency dpa.
The dioxin scandal broke at the start of this week, forcing more than 1,000 farms to cease output and prompting a cull of 8,000 chickens.
The briefing paper was prepared for a committee of the German parliament. On Tuesday, officials had spoken of just 527 tons of contaminated feed.
The additive, fat to give animals energy, was sold to 25 German feed manufacturers who use grain and recycled substances as ingredients.
Seven shipments totalling 3,000 tons by the fat manufacturer from November 12 to December 23 were under suspicion, the paper said.
The fat then made up 2 to 10 per cent of the mixture for poultry and pigs. At a maximum, that could mean 150,000 tons of feed were contaminated. Public health officials say the concentration of dioxin was minute and does not pose any real risk to human health.
A company operating north of Hamburg, Harles and Jentzsch, has been identified as the provider of the suspect fat.
The report said the company admitted to "human error" in using fatty acids that were not cleared for animal consumption in its manufacturing process. Police are investigating the company.
The fatty acids were apparently a by-product from another company which processes used cooking oil into diesel fuel.