Vegan protesters on Monday launched a cross-border campaign targeting a busy Melbourne street, plus abattoirs and farms in Victoria, NSW and Queensland.

It resulted in scores of arrests, criminal charges and a renewed call for farmers to take action, with the federal government committing to underwrite legal claims.

"If there are pastoralists and farmers that are in a position to actually bring a civil action against these groups ... then the Commonwealth is totally open to supporting them in a test case," Mr Morrison said.

"State and territory governments should ensure that the full force of the law is brought against these green collar criminals."

Earlier in the day, the prime minister slammed the actions of Aussie Farms, the group allegedly behind the protests.

"It is shameful, it is un-Australian," he told 2GB radio.

Privacy laws were changed last Friday which exposes Aussie Farms' website to significant penalties for publishing farmers' addresses and contact details.

Attorney-General Christian Porter on Monday went a step further, writing to the Australian Information and Privacy Commissioner, asking for an investigation.

"There are strong grounds to conclude that Aussie Farms is engaging in a systematic effort in collecting, using and disclosing personal information to the detriment of farmers and agricultural producers," he wrote.

A popular cafe in West Gippsland announced on Sunday it has closed, blaming "threats from the abusive vegan activists".

Mr Morrison said it was wrong that farmers should be targeted when they are doing it tough during the drought.

Monday's protests coincided with the first anniversary of a film documentary, lobbying against animal cruelty.

"The industry is telling people these animals are being killed ethically, that they are being killed humanely. The reality is ... it's the furthest thing from humane," documentary director Chris Delforce told AAP.

The group wants state and federal agricultural ministers to "acknowledge cruelty in the process of killing animals for food, clothing and entertainment" and to add warning labels on animal products.

Vegan protesters chained themselves to machinery at abattoirs in Queensland and NSW, while the intersection of Flinders Street and Swanston Street was shut down in Melbourne during morning peak hour.

Forty people were charged following the protests in Melbourne's CBD. Nine people were charged at Goulburn in NSW after chaining themselves to a conveyor.

The owner of an abattoir in Queensland reportedly gave three lambs to animal rights activists in exchange for ending their protest in Yangan.

Nationals senator John Williams said there could be "punch-ups" if protesters continued targeting farmers.

"Farmers are not violent people. But when these people go out there and cut the fence and let the livestock out on the road, well farmers might get angry," he told Sky News on Monday.

Australian Associated Press