An Australian abattoir has been shut down after footage emerged showing "gross mistreatment" of animals, less than a year after Canberra suspended its live cattle trade to Indonesia due to cruelty concerns.

Regulators late Thursday said they had stopped the slaughter of animals at the Sydney plant after viewing images of sheep, cattle, goats and pigs being killed, including pigs being smashed on the head with a metal bar.

"There is no denying that the footage is disturbing. I'm shocked. I think it is the worst case I've seen in an abattoir in terms of animal welfare breaches," the New South Wales state Food Authority's Peter Day told reporters.

The incident comes after Australia abruptly froze all cattle exports to Indonesia last June over animal welfare issues, when state broadcaster ABC showed images of animals being kicked and mistreated in Indonesian abattoirs ahead of slaughter.

Trade was reinstated several weeks later after Jakarta agreed to a strict new permit system requiring exporters and slaughterhouses to guarantee animal welfare standards, but the Australian cattle industry was badly impacted.

In the latest incident, footage shown on the ABC showed a worker repeatedly hitting a pig on the head with a metal bar, while another pig was beaten several times because it had not been stunned adequately beforehand.

Day said the footage was not representative of the industry as a whole, describing the incident as a "rogue" action which was in no way compliant with what was expected of abattoirs.

The abattoir, Hawkesbury Valley Meat Processors, said the casual staff involved had been sacked or given other duties, adding it would cooperate with an ongoing investigation into the allegations.

But the issue has again highlighted the treatment of animals in slaughterhouses, with animal advocates calling for closed circuit television cameras in Australian abattoirs to prevent any mistreatment.

"One of the problems is that unlike export abattoirs, domestic abattoirs don't have an inspector or government officer on site most of the time," Animals Australia's Lyn White said.

"Only the presence of cameras will actively discourage workers from engaging in such wanton acts of gross cruelty."

Australian law requires that "animals are slaughtered in a way that prevents unnecessary injury, pain and suffering to them and causes them the least practical disturbance".

Fines of up to Aus$110,000 (US$118,280) or jail sentences of two years apply for acts of aggravated cruelty to animals.