Animal rights activists have clashed with authorities at the scene of a truck crash involving 6,000 chickens on the New South Wales north coast.

A male driver in his mid 30s was taken to the Lismore Base Hospital with minor injuries after his rig rolled on the Bruxner Highway at Goonellabah just before 7:00am.

Kelly Nelder from the Sugarshine Feminist Animal Rescue Mission Sanctuary, which takes in unwanted farm animals, arrived at the scene after being alerted by other activists.

"When we arrived we saw a pretty horrific crash site. There were a lot of dead chickens right near the overturned truck," she said.

An animal rights activist with an injured chicken. ( Supplied: Sugarshine FARM Sanctuary )

"When we got there we started to take a few photos and then we saw one of our teenage volunteers running up a hill away from the crash site and she was being chased by two fire officers.

"She'd found an injured chicken and was trying to take it to a vet and was very distressed.

"The police and the firefighters actually escorted us back inside the crash site … they were wanting to get our names and telling us to stay in one spot and telling us that the chicken was property and what this woman was doing was the same as shoplifting."

Ms Nelder said the volunteers had explained they wanted to take the chicken to the vet.

"After some discussion with police we've just taken the chicken, who we've named Clarabelle, to the vet and she's in reasonable condition, although she's in shock right now," she said.

"It was certainly distressing to see all of these animals. Some had had their heads cut off in the incident. There were chickens flapping around obviously in pain.

"You can only imagine if that had been a truck full of crates of puppies, how much of an impact that would have had on people."

Human safety vs animal welfare

North Coast Local Land Services district vet Phil Kemsley said it was not possible to estimate how many chickens had been killed in the crash and how many would have to be euthanased.

"Human health and safety is paramount in this situation, [but] we've also got to balance that against animal welfare," he said.

A vet says it is hard to estimate how many chickens have been killed in the crash. ( Supplied: Sugarshine FARM Sanctuary )

"You've got crates on their sides [and] we can't have people going in and under crates.

"Although we'd love to be able to redeem those birds that are under there, we just cannot do that because it's unsafe to do so."

The broiler chickens were on their way to the Darwalla abattoir at Mount Cotton in Brisbane for processing.

The Darwalla Group has declined to speak to the media, but has confirmed it has started an internal investigation into the incident.