Pork tainted with the highly toxic chemical dioxin may have been sold in Germany, authorities said on Wednesday.

German and European Union authorities are struggling to contain a health alert, which began on January 3 when German officials said dioxin-tainted feed had been fed to hens and pigs, contaminating eggs and poultry meat at the affected farms.

On Tuesday, German authorities said dioxin had been found in pork for the first time during the alert.

The state government in the northern state of Lower Saxony on Wednesday confirmed that pork from at most 100 pigs from a farm in the state which had received contaminated feed had been sold before the farm received a closedown order.

Lower Saxony authorities had previously said it believed no tainted meat had been sold.

No sales were made after the farm received its closedown order (in early January) but we cannot rule out that some sales were made before it received the order, a state agriculture spokeswoman said.

State deputy Agriculture Minister Friedrich-Otto Ripke said separately on German television ARD: Before the closure, goods were brought into the market but we do not know with what dioxin exposure.

This must now be investigated before we can talk definitively about any danger to consumers.

Prosecutors in Germany are investigating the cause of the contamination and specifically whether industrial fats and feeds company Harles and Jentzsch distributed fatty acids meant for industrial paper production to animal feed processors.

China on Wednesday suspended imports of pork and egg products from Germany because of dioxin fears, following an earlier move by South Korea.

German Agriculture Minister German Farm Minister Ilse Aigner said a major dioxin monitoring system was needed for the animal feed industry.

Food and industrial product flows must be separated and harsher punishment must be imposed on those who break health regulations, she said on the television channel ARD.