Dresden, Germany - Bird flu has returned to Germany, with the H5N1 influenza virus breaking out among farm ducks in the eastern state of Saxony, officials said Thursday.

It was the first proven appearance of the disease this year in Germany. Officials were preparing to slaughter the whole flock of ducks at Goerlitz, near the Polish border.

Germany's national animal health laboratory on the Baltic island of Riems said the find was "somewhat surprising" as the infection alert had been reduced to moderate after an outbreak was beaten last December.

It remained unknown what proportion of German wild birds were infected, a spokeswoman said. Currently none of Germany's neighbours were reporting any H5N1 finds and the virus had only shown up in Asia in recent months.

The virus can infect people if hygienic precautions are not followed and can kill, but human-to-human infection has only happened in very rare cases, mainly in Asia. Scientists fear the virus could mutate into a human disease causing mass death. (dpa)