BERLIN (AFP) - German health officials on Tuesday confirmed that the potentially lethal H5N1 strain of bird flu had been found in wild swans in the east of the country, the second such incident here in a week.

The three birds were found dead in the area around Frohburg, near Liepzig, second incidence of the feared virus in a week, the Friedrich Loeffler Institute reported.

The discovery followed the confirmation on Sunday of six cases of H5N1 in wild birds found dead near Nuremberg, 200 kilometres (120 miles) further south.

In Frohburg, a three-kilometre security cordon has been set up around the area where the swans were found. All poultry within this area must be kept indoors and dogs and cats are being kept on leads.

The Frohburg case was the second case of the flu strain found in Germany this year, and the third in Europe.

Last week, H5N1 was discovered on a turkey farm in the Czech Republic, and 6,000 turkeys were subsequently slaughtered.

Germany has only recorded one incidence of the feared virus on a farm, in April 2006, after which more than 21,000 poultry were killed.