BERLIN (AFP) - Three wild birds in Germany have died of the feared H5N1 strain of bird flu, a health official in Nuremberg in southern Germany said on Sunday.

Katja Guenther told AFP tests carried out by the Friedrich Loeffler Institute confirmed that two swans and a wild goose had been infected with the H5N1 strain of the virus.

She said tests were being conducted on another seven birds, mostly swans, which had died of bird flu to see whether they too had been carriers of H5N1, which is potentially lethal for humans.

The dead wild birds infected with the virus were found at two lakes near Nuremberg in the past week.

Guenther said local authorities had cordoned off an area with a four-kilometre (2.5-mile) radius from where the diseased birds were found.

Nobody will be allowed to bring birds into the area or take them out from there for the next three weeks, and poultry in the area must be kept indoors for the same period.

The Friedrich Loeffler Institute was reported as saying the new German cases of H5N1 avian flu could be related to an outbreak of the virus in the Czech Republic.

H5N1 was found on a poultry farm in the central Czech Republic last week, prompting the slaughter of some 6,000 turkeys.

Germany battled a bird flu epidemic last year. It broke out on the Baltic Sea island of Ruegen and spread to six of the country's 16 states, including Bavaria.

The disease spread to mammals, infecting three cats and a stone marten, but did not affect humans.

The last reported case in Germany of the highly pathogenic strain of bird flu was reported in Dresden in August last year. It killed a swan in the eastern city's zoo.

According to the World Health Organisation, bird flu has claimed more than 130 lives worldwide since 2003, mostly in southeast Asia.