HAMBURG (Reuters) - The poisonous chemical dioxin had been found above permitted levels in eggs from a German farm following discoveries at six other farms in the country in April and May, officials said on Wednesday.

The poultry farm is in the Emsland area in the north German state of Lower Saxony, the state agriculture ministry said.

The farm with its 12,000 chickens has been quarantined and its eggs recalled from sale, it said. The dioxin was discovered by the farm's own safety checks.

The ministry said there was no acute danger to public health because dioxin is dangerous only if consumed over long periods. Small doses are not harmful.

The previous dioxin discoveries were in eggs at farms in Lower Saxony and the neighboring state of North Rhine Westphalia. In January 2011, an European Union-wide health alert was sparked when German officials said animal feed tainted with dioxin had been fed to hens and pigs, contaminating eggs, poultry meat and pork at affected farms.

Germany then introduced a series of measures including restrictions on animal feed ingredients and increased inspections of farms and feed.

(Reporting by Michael Hogan; Editing by Pravin Char)