The Ministry for Primary Industries has identified three new South Island properties that are positive for the bacterial cattle disease mycoplasma bovis, bringing the total to six.
"All three properties have links to existing infected properties, and this is an entirely expected pattern at this stage of the response," MPI response co- ordinator David Yard says.
Two of the newly identified properties are Van Leeuwen Dairy Group farms and were already under Restricted Place notices under the Biosecurity Act, while the third is a lifestyle block near Rangiora.
"We have no evidence of any means of disease spread other than close animal contact, at this stage," Mr Yard said.
"This includes the disease having jumped fences - which our scientists and vets tell us is highly unlikely to occur."