The H5N1 bird flu virus has been found in a weasel-like mammal called a stone marten, a German laboratory said Thursday, indicating the disease has spread to another animal species.

The Friedrich-Loeffler Institute confirmed the presence of the virus in the marten, a carnivorous mammal with brown fur and a white throat patch. The animal was found sick and apparently dying on the island of Ruegen in northern Germany on March 2.

It was then killed by a government veterinarian, the institute said in a statement.

The deadly strain of bird flu was found in a cat on the same island last month, the first time the virus has been identified in an animal other than a bird in central Europe. Infected cats have since been found in Austria.

"The presence of an H5N1 infection in a second mammalian species is not surprising," Till Backhaus, the regional minister for agriculture, said in a statement. "Cats and martens have a comparable prey spectrum."

Cats are believed to have caught the virus by eating infected birds.