German authorities ordered the slaughter of hundreds of pigs Tuesday as the nation's dioxin scandal widened beyond poultry and eggs.

The top agriculture official in Lower Saxony state in northern Germany called for the animals to be killed after tests showed illegally elevated levels of dioxin in swine at a farm in Verden.

The farm was known to have purchased tainted feed from the company believed to be responsible for the scandal over dioxin, a cancer-causing chemical.

German firm Harles & Jentzsch GmbH, which produced fat used in tainted feed pellets, is being investigated on allegations it did not alert authorities to the tainted product for months. Samples of the fat contained more than 70 times the approved amount of dioxin, according to tests by the Schleswig-Holstein state agriculture ministry.

"We were specifically investigating this farm, because they had bought their livestock feed from Harles & Jentzsch, the company that delivered tainted feed to all the other farms that had to be banned," Lower Saxony's agriculture minister, Gert Hahne, said.

Hahne did not know exactly how high the dioxin levels in the pigs were but said they were above the allowed maximum.

The scandal broke last week when German investigators found excessive levels of dioxin in eggs and then some chicken meat. Authorities froze sales of poultry, eggs and, as a precaution, pork, from thousands of farms.

Farms still closed

Some 558 farms remained closed on Tuesday, said Holger Eichele, a spokesman for the federal agricultural ministry in Berlin.

Agriculture Minister Ilse Aigner said Monday that, while the tainted products posed no direct health risk to humans, officials were working nonstop to find out who and what had contaminated the feed sent to thousands of farms and vowed tough legal action against those responsible.

She said companies should be banned from producing both industrial fats and fats used for livestock to avoid the possibility of industrial fats ending up in animal feed. Harles & Jentzsch chief Siegfried Sievert has said the company believed that byproducts from palm, soy and rapeseed oil used to make organic diesel fuels were safe for use in livestock feed.

Aigner said her ministry was in talks with the European Union on better controls and monitoring and she was confident they could "find a common European solution."

Danes watching

In Denmark, the Danish Veterinary and Food Administration said Tuesday that it was closely monitoring the German developments and that the tainted feed had also been bought by a Danish company and given to hens.

At present, if consumers eat the eggs, "there are no health problems," said the government agency, which is also investigating where the eggs may have been used. The hens were bred for laying eggs and not for slaughter.

The EU's food safety system warned Danes on Sunday about the tainted German feed entering Denmark.