Germany said it would start testing ducks and geese for bird flu prior to slaughter, after two cases of the highly infectious H5N8 strain were detected in a week.

The emergency procedure, which will take effect Tuesday, requires all duck and geese farmers across Germany to have their animals tested for bird flu before being transported, the agriculture ministry said.

"The animals can only be transported and slaughtered in the case of a negative test result," the ministry said in a written statement.

It said the test must be carried out no more than seven days before transport.

Unlike turkeys and chickens, ducks and geese display no symptoms when they are infected with H5N8.

This creates a risk that infected animals are taken for slaughter, spreading the infection via contact with the vehicle or people.

"This measure is for the protection of our animal populations," Agriculture Minister Christian Schmidt said in the statement.

The measure, which comes into force at midnight, applies across Germany until the end of March.

In the last week, two cases of bird flu have been found at different farms in Lower Saxony state.

"There was no contact between the two farms," the ministry said, adding that experts assumed that migratory birds had likely spread the virus.

Some strains of avian influenza are fatal for birds, and pose a health threat to humans, who can fall sick after handling infected poultry.