Rodeos are illegal and must be banned, a new report from the Animal Law Association says.

Photo: Anti-Rodeo Action

The just-released report calls on the government to act, saying the way animals are treated at rodeos goes against the Animal Welfare Act and the sport cannot legally continue.

Its author, Catriona MacLennan, said the Rodeo Code of Welfare was flimsy, outdated and illegal according to the Act.

"It allows for use of electric prods and flank straps and spurs and ropes being thrown around young calves necks, and young cows being slammed onto the ground.

"If you look at the main Act, it's quite clear that all of that is contrary to, and banned by, the main Act," she said.

Ms MacLennan's assessment matches a 2015 internal Ministry for Primary Industries memo that said rodeos could be prosecuted if it wasn't for the welfare code.

She's calling on the government to "adhere to the law" and ban rodeos.

However, the Rodeo Cowboys Association said the report was a stunt. It said rodeos were not illegal and animals weren't harmed.

Associate Minister of Agriculture Meka Whaitiri will receive the report at Parliament at 6pm.