French Prime Minister Dominique de Villepin has urged cat owners not to let their pets stray into areas affected by bird flu.
There have been feline fatalities from bird flu in Asia
The advice comes after a dead cat tested positive for the lethal H5N1 strain of the virus in Germany.
The domestic cat, found on the virus-hit Baltic island of Ruegen, was the first EU mammal to die of bird flu.
France is already vaccinating thousands of free-range poultry after 15 wild swans were found to have H5N1.
"Adhering to the principle of precaution, cat owners are asked not to let them stray in zones where the H5N1 virus has been detected," Mr de Villepin said at his monthly press conference.
H5N1 does not yet pose a large-scale threat to humans. However, experts fear the virus could mutate and trigger a flu pandemic, potentially putting millions of human lives at risk.
Deaths of domestic cats, tigers and a panther from H5N1 have been recorded in Asia.
Tests are continuing on the German cat to determine if it is the exact strain that has been found in birds.
In the mean time, cat owners in Ruegen, where more than 100 wild birds have died since mid-February, have been told to keep their pets indoors.
The World Health Organization says there is no present evidence that domestic cats play a role in the transmission cycle of H5N1 viruses. To date, no human case has been linked to exposure to a diseased cat.
Elsewhere in Europe, Sweden has detected "aggressive" bird flu in two wild ducks and is testing to confirm H5N1.
On Tuesday, German government officials said H5N1 had been found in the southern state of Bavaria, the fifth German state to report cases.
And in Romania, samples of domestic fowl found to have the H5 virus were being tested for the H5N1 strain, the agriculture ministry confirmed.