French authorities say four ducks have tested positive for the H5N1 strain of bird flu in northeastern France.

The ducks were found dead last week in an area known as Diane Capelle in the Moselle region.

Two dead swans had already been discovered with bird flu at the end of July in the same area.  The site is just 10 kilometers from where three other swans were found dead with the virus about a month earlier.

That outbreak was the first in France in more than a year.

Authorities have extended the bird flu alert level in the area bordering Germany and Luxembourg. Residents are required to lock up their domestic birds and poultry or surround them with nets to prevent contact with wild birds that may carry the virus.

World health statistics show the H5N1 strain has killed 193 people globally since outbreaks in Asia in 2003.  No human deaths have been reported in Europe.

Some information for this report was provided by AFP and AP.