Mycoplasma bovis has been confirmed on two properties in Hawke's Bay and Canterbury.

The Ministry for Primary Industries said they were a Hawke's Bay beef farm in Poukawa with 36 animals and a beef farm near Ashburton with 204 animals.

The farms were linked to other known infected properties through animal movements and tracing work from them was under way.

The number of active infected properties in New Zealand stands at 42.

There are 70 properties with Restricted Place Notices, meaning they are infected or suspected of having Mycoplasma bovis.

The Hawke's Bay A&P Society said last week it expected to decide this week whether to go ahead with its drawcard stock class at the Royal New Zealand Show or put a decision on hold.

MPI and Dairy NZ have been in close contact with the Royal Agricultural Society over the crisis, with particular interest in the eastern North Island region where the northern show season starts.

Calf classes in children's animal showing sections have already been cancelled. The North Island season-opening Poverty Bay Show in Gisborne on October 12-13 will be without its Supreme Heifer Challenge, now set to be staged on the property of sponsors Turihau Station, and the Wairarapa A&P Society announced this week it has cancelled the cattle classes at its show at Clareville, near Carterton, on October 27-28.

The Egmont show in Taranaki in November has also abandoned its cattle classes, while in the South Island the Winton A&P show in Southland last January went ahead without cattle classes, as did the Oxford and Hawarden shows in North Canterbury in March and April.

Royal Agricultural Society beef section chairman Mark Fleming said cattle will also be absent from the Ellesmere and Ashburton shows in Canterbury, both in October.