An official in North Rhine-Westphalia state said more than 100,000 potentially contaminated eggs had been distributed from two farms over the past two weeks. Only eggs sold before the problem was first noticed on 23 December could be affected.
"I cannot say exactly how many possibly contaminated eggs were distributed, but they have been found on two farms in the state," NRW state environment ministry spokesman Wilhelm Deitermann told Reuters.
"We are doing everything we can to inform consumers about possible contamination of eggs," he said.
More than 8,000 hens had to be culled on one farm alone, Deitermann said, though the decision to kill animals testing positive for dioxin so far rests with the farmers.
The origin of the feed contamination has been traced to a distributor of oils for animal feed production in the northern state of Schleswig-Holstein, where oils meant for industrial use in biofuels were distributed for animal feed.
The government of NRW posted all the serial numbers of eggs that could be contaminated on its website.
Newspaper websites quoted consumer protection groups saying that people should avoid eating fresh eggs until further information was available, while it was unclear how other products such as poultry and pork meat could be impacted.
"It is still unclear which precise products are affected," Spiegel magazine's website quoted Regina Aschman of a consumer protection group in Bremen as saying. Some media said organic products were not affected.
Feed company cited by prosecutors
In Lower Saxony, meat production has been halted at some 1,000 farms, said Friedrich-Otto Ripke, the state secretary for agriculture and consumer protection.
He called for damages to be paid to the farms affected, saying: "I hope and expect that [...] the guilty will be severely punished."
"For those farms that are currently closed for business - who cannot earn money but still have costs - the question will be about compensation," Ripke told Reuters.
A prosecutor in the state opened preliminary proceedings on Tuesday against a feed company called Harles und Jentzsch. The company told Reuters it had no comment about the investigation at the moment but would issue a statement to the media later.
Prosecutor Ralph Doepper told Reuters that a conviction on charges of violating German animal feed laws can carry a sentence of up to three years in prison or a fine.
At the European Commission in Brussels, a spokesman said there was no need to ban German food exports because the dioxin contamination has so far only affected Germany.
Dioxins are toxins formed by burning waste and by other industrial processes and have been shown to contribute to higher cancer rates and to affect pregnant women.
(EurActiv with Reuters.)