Media playback is unsupported on your device Media caption Farmers 'sent death threats by vegan activists'

Veganism has been described as the fastest growing lifestyle movement. For some concern about animal welfare leads them to actively campaign against all forms of the meat industry. But are some of those activists taking it too far?

"When you're being called murderers and rapists, that is overstepping the mark, for fairly obvious reasons," says Alison Waugh, a trainee farmer in Northumberland.

She has received death threats due to her work and told the Victoria Derbyshire programme other farmers are feeling threatened.

"Which is quite ironic from people that want peace for animals, but then they tell you, 'I hope you and your family go die in a hole for what you do,'" she says.

"You've got people storming the meat mart, spraying graffiti...that's when it's not OK, when you've got people worrying if their cows are going to be safe tonight."

One activist group is called the Save Movement, which says it has a non-violent approach to campaigning. It has 42 groups in the UK and 100 worldwide.

Its activists hold vigils outside abattoirs and aim to turn the world vegan by sharing images on social media of the animals' treatment.

Bear witness

Lead activist and Instagram star Joey Carbstron and his team wait for hours until trucks of animals are on the move in order to, as they put it, "bear witness" to what the creatures experience.

Image caption A video shot by Joey was seen by 17,000 people

"These days we have tech like iPhones, we can bring their faces out to the public and say, 'This is where your food comes from'. We get people to connect with the animals," he says.

There have also been cases of activists standing in the meat aisles of supermarkets with graphic images and noises of animals being slaughtered.

During filming for this programme, they saw an opportunity to take their protest a step further.

At a slaughterhouse in Liverpool, some activists decided to trespass on the property when the pigs were not brought through the front entrance.

Police were called and escorted them off the property, following a tense argument between protestors and workers.

The footage was spread across the Save Movement Facebook and Instagram accounts. It had 17,000 views on Joey's YouTube and 4,500 shares.

'Cannot sleep'

The Vegan Society describes veganism as "the fastest-growing lifestyle movement," with demand for vegan and vegetarian food increasing ten-fold last year.

Research by Ipsos Mori in 2016 suggested at least 542,000 people - or 1.05% of the 15-and-over population in England, Scotland and Wales - were following a vegan diet.

Ten years earlier the estimated number of vegans was just 150,000.

The society says it does not condone any illegal activity, but provides evidence-based information on issues related to veganism. It is currently funding academic research to understand what prevents people from being vegan and how best to make them change.

But some vegan activists are calling farmers who have raised animals for generations murderers for killing animals, or rapists for taking their milk.

The National Pig Association claims its members "cannot sleep at night" because Save Movement members have allegedly turned up at farms and slaughterhouses at night.

The Association of Independent Meat Suppliers has met with the official National Counter Terrorism Police Operations Centre team to discuss how to respond to the movement.

Alison says she objects to the suggestion that farmers exploit their animals. "It's crushing when you take as much pride in your animals as we do.

"I don't think they can understand, or differentiate between the fact that different animals have different purposes. We have these companion animals and we have our livestock and there is a line drawn there."

'Sick society'

But Joey disagrees with the UK's reputation as caring about animals.

"Their actions don't reflect that. When they buy a chicken breast, that was torn off an animal that didn't want to die. We can't love animals whilst we're consuming their flesh or paying for them to go into a slaughterhouse," he says.

"Slaughterhouse workers are a product of a sick society who want to consume animal flesh."

He denies being an extremist, saying that people have to understand that what is happening to animals is extreme.

"If it were dogs in there, people's pet dogs, they'd be helping us, the public would be helping us stop those trucks, the public would be trespassing too."

But Alison says the farmers will not take their action lightly.

"There is an attack on the industry, and that is an attack on me, people like me, my family. We will forever eat animals and I'll keep fighting for this industry as long as I can," she says.

Watch the BBC's Victoria Derbyshire programme on weekdays between 09:00 and 11:00 on BBC Two and the BBC News channel.