Extremists "inspired by millionaire Gareth Morgan" are accused of deliberately killing cats in Northland, sparking a bitter fight between conservationists and cat-lovers.

Images of cats caught in traps - described by cat supporters as "horrifying" - have been posted on a Far North conservation group's Facebook page.

But cat-lovers are accused of extremism too - sending abusive and threatening emails to community board members considering the fate of a controversial cat colony, sparking complaints to police.

The ugly spat centres on a colony of about 10 strays being fed on a council reserve in Paihia in the Bay of Islands.

Morgan labels the colony "vile" and a threat to wildlife. But its supporters describe themselves on Facebook as "soldiers" in the "Battle of Paihia". Their "war" is against conservation group Bay Bush which seemed to revel in posting photos of dead cats on Facebook, and a community board that last week voted to remove the stray cats permanently.

Their hate figure is Morgan, the businessman and philanthropist turned anti-cat crusader. Auckland Cat Coalition member Anne Batley-Burton squarely blames him for the trouble.

"Gareth Morgan is inciting the conservationists and getting them all worked up about the cats going out and killing all the birds. It's causing so much trouble between people in communities."

Another Cat Coalition member, Diane O'Connor, believed Morgan's crusade had encouraged "radicals" to harm cats. "There are extreme people who now think, ‘yay, we've got the green light to hurt, maim and make animals suffer'."

She said some of the cats were caught in possum traps that had been converted especially to lure them.

The Bay Bush Action Facebook page featured images of trapped cats, including one graphic picture of a black tom hanging by its mouth.

Several people commented on the page that the pictures were like something

from a horror movie and were inappropriate, but others cheered on the killers. "Well done . . . I wonder how many baby kiwi that evil cat killed," one post said. The images have since been removed, the group conceding they were inflammatory.

Group spokesman Craig Salmon said Bush Action posted one of the images, of the black tom in a Landcare Research-approved trap. "It looks more gruesome than it is. It's an instant kill trap, it's humane," he said.

Other images of cats with their heads stuck in possum traps were posted by "spurious" people not connected with Bush Action. The group did not use that style of trap. Salmon said that although the Department of Conservation considered any cat on its land a pest, Bush Action was operating "deep in the bush" and trapping only feral cats.

Meanwhile, two members of the Bay of Islands-Whangaroa Community Board have complained to police after a Facebook group called Cats to Stay - set up in opposition to Morgan's website Cats to Go - encouraged cat lovers from around the world to email councillors and Far North Mayor Wayne Brown ahead of a meeting last Wednesday to decide the fate of the Paihia strays.

"It was severe harassment," said deputy chair Belinda Ward. "I'm a ‘terminator', a ‘murderer', a ‘cat killer'. I had three days of bombardment. It educated me that cyber bullying by extremists is alive and well."

Brown inflamed the situation when he wrote back to an American cat lover: "You are a total dickhead, stop killing Iraqis and Afghans, they are just bird-eating cats and your stupid emails are only guaranteeing that the cats will all end up in Asian rice stews."

Paihia police confirmed a complaint had been received, but it was too soon to know what action police might take.

The board voted on Wednesday to get rid of the colony despite pleas from the SPCA. Morgan applauded the decision as "courageous" and said it was a small victory against the SPCA and "ignorant cat nutters" who were undoing good work to protect birds and geckos in the area.

O'Connor said the decision was "immoral" and vowed that the fight had only just begun.

Betty Chapman, 86, of Paihia, who has been feeding the cats for 10 years, will keep feeding them even though she no longer has permission to do so.

"We can't let the animals starve," she said. She, too, has gone to police in the past - over vandalism, or what she calls "sabotage", of the cat feeding station.

Bird-lover Carol Davies of Kerikeri, a member of the Ornithological Society, said Morgan had made it acceptable to talk about the threat cats posed to native wildlife. "It's something that everybody's scared to talk about," she said.

"We had to speak about it behind closed doors. What I found was [Morgan's comments] meant we came out of the closet."

Davies laid an assault complaint with police last year, claiming she was pinned against a wall by a woman in her 70s connected with the cat colony and told she wasn't welcome in town.

Some of the cat feeders believe Davies vandalised the feeding station. She denies it: "What would I do that for?

"These people are so driven by their self-centredness, they're just all about ‘me, me, me'."