MELBOURNE (Reuters) - Australia police arrested 38 animal rights activists on Monday after they blocked peak hour traffic in Melbourne in protests to mark the first anniversary of a film, Dominion, about factory farming.

The protests were part of a wave of action in three states, where activists targeted abattoirs in the middle of the night to protest cruelty to animals.

The documentary Dominion, directed by Chris Delforce, used drones and undercover footage to film feedlots and saleyards to show how animals are treated in the production of meat, dairy, eggs and leather.

“The industry is telling people these animals are being killed ethically, that they are being killed humanely,” Delforce told Australian Associated Press. “It’s the furthest thing from humane.”

Protestors blocked a major Melbourne intersection for two hours, stopping trams bringing thousands of commuters into the city. Further down the road, activists blocked the entrance to Melbourne’s aquarium.

Police said they had not been told in advance about the protests.

“We respect the right for people to protest peacefully but we will not tolerate anti-social behavior that disrupts the broader community,” Victoria police superintendent David Clayton said in a statement.

Prime Minister Scott Morrison, in campaign mode ahead of an election in May where farmers’ votes will be key, called the vegan protestors’ plans to storm farms and abattoirs shameful, and that the government would tighten laws to curb such action.

“I mean this is just another form of activism that I think runs against the national interest. The national interest is people being able to farm their own land,” Morrison said in an interview on 2GB radio.

In Yangan in Queensland state, 18 activists chained themselves to fixtures inside an abattoir early morning on Monday and eventually left after management agreed to release three sheep, Queensland police acting inspector Jamie Deacon told a media conference.

No charges have been laid against anyone, he said.