DoC says the killing of kiwi in Northland is the worst it's seen in almost a decade.

Massey University vets have confirmed the deaths of at least seven kiwi in Kerikeri are the result of dog attacks.

Conservation Services Manager Rolien Elliot says she's never come across so many deaths in such a small area.

The first death was discovered in late May.

South Kerikeri Inlet Landcare founder Mike Thompson says his members are saddened and disappointed somebody has let their dog loose.

"We're doing our best to kill other pests to try and attract kiwi back..and then you get a huge chunk of a population taken out by a rogue dog."

He says the group is doing their best to kill pests and to have a rogue dog destroy their efforts is disappointing.

The Department of Conservation is working with the Far North District Council to track down the rogue dog, or dogs.