A fiery exchange on Seven Sharp has seen the head of animal rights group SAFE hurl an expletive at host Mike Hosking after he said the group will be "undermining us as a country" by releasing graphic video internationally showing mistreatment of bobby calves.

The video, revealed by TVNZ's Sunday programme, showed baby cows thrown into trucks, being crammed into cages, and kicked.

The group that filmed the footage says it wants to show the rest of the world that milk from New Zealand is made through cruelty to animals.

Hosking last night put to SAFE executive director Hans Kriek that "the moment you go international you're undermining us as a country. It's bordering on espionage to deliberately go out and undermine an industry for your own purposes".

Mr Kriek hit back, saying: "No. It's not for our own purposes. It's for the purposes of better animal welfare in this country. That's really important. We get nothing out of this except for sh** from people like yourself."

Hosking tried to chip in with: "But, well, no, well see maybe maybe..."

But Mr Kriek cut him off, insisting: "No, no, no, no, no, no, let me just finish, let's finish. It's really important to point out that for one a lot of good is already coming out of this. That abusive slaughterhouse worker - fired. One of the people throwing these animals - fired. And it's only happening because we exposed it."

Asked if he worries that SAFE is getting increasingly radical and losing touch with "wider New Zealand", Mr Kriek said: Yeah, that's a possibility and we acknowledge that. For some people that is the case."

But he said a lot of other New Zealanders "realise that if we want to see some meaningful change in this industry we have to have that stick behind the door and it will be used if we have to".

Mr Kriek said releasing the video internationally is "the stick behind the door".

"We want real change and we know that the threat to our international reputation is going to make sure that something will get done in this country."