The owners of a Christchurch bar say two patrons who were choked unconscious by security staff were drunk and making death threats and it's standing by its bouncers.

Disturbing video shows one man choked out and unceremoniously dumped on the pavement.

It's only the presence of the recording camera that seems to prompt the bouncer to put the man in the recovery position.

"They handled it in a nature that we've been told was necessary for the situation. There were passers by. If one of those gentlemen hit a passer by then what would have happened then?" Orleans bar general manager Rick Stevens told ONE News.

They handled it in a nature that we've been told was necessary for the situation - Rick Stevens, bar manager

But New Zealand Security Association director of training, Stuart O'Reilly says it's not a bouncer's job "to assault members of the public".

A second drinker was also rendered unconscious in an instant while the camera was blocked.

This footage from Saturday night was released to media rather than police who are now looking into the incident.

"It would be interesting to know if the gentlemen involved have been trained and hold certificates of approval. If they have, they must have forgotten some of the things they were taught," Mr O'Reilly said.

The bouncers work for Wolfgang Security. Their head office was empty today and the phone went unanswered when ONE News called.

The bar's owners say the additional security footage shows the men making death threats and threatening to hit the bouncers, and they'll release it should police ask.

"They were protecting not just themselves but the other patrons around that area, 'cause we had a queue of over 60 people standing right there. And if they threw into them who knows what could have happened," Mr Stevens said.

No complaints have been made to police or charges laid in relation to the weekend incident.