Escalating tensions between livestock farmers and vegan activists have sparked accusations of “intimidation” on both sides, following a change in the way roadside protests are policed.

The fine line between the lawful right to protest and the right for traders to go about their business has come into sharp focus at Norwich Livestock Market on Hall Road.

Animal rights activists have been holding regular “vigils” at the fortnightly sale for the last five years – but tensions have been rising in recent months.

Since last autumn, Norfolk police officers have permitted placard-waving protesters to stop livestock trucks on the access road for 30 seconds, to film and photograph their animals.

It often provokes angry confrontations, and the latest flashpoint on Saturday resulted in two arrests, one farmer and one protester, which police are still investigating.

Market chairman Stephen Lutkin claimed the protests had crossed a line into “intimidation”, and criticised “inconsistent” policing, with the time limit often broken and vehicle drivers also being directly filmed and harassed.

But Norfolk police said all protests were handled “fairly and proportionately” – with officers applying their judgement within a “subjective” new legal precedent which means protesting in a way that obstructs road users is not automatically a criminal offence.

And the protesters responded by saying that they were the ones being intimidated by farm vehicle drivers while carrying out their “peaceful protests”.

Mr Lutkin said: "Everyone has their right to protest, and I don't have a problem with that, but this is harassment and intimidation.

"It wasn't too bad in the early stages. But within the last eight months, the police have allowed the protesters to stop everyone for 30 seconds so they can film the livestock in the back of the trailers. It is getting more aggressive and there has been issues with them filming people in the cab as well, and a lot of farmers have complained because they feel intimidated.

"It is a difficult one for the police, but we do have an issue with inconsistency as to how it is policed because we don't get the same sergeant in charge each time. One might be a stickler for the rules, and then you get another one with a completely different attitude and they [the protesters] are allowed to get away with more.

"That is what antagonises the farmers. Sometimes they will be stopped there for two minutes.

"I never agreed to the 30 seconds, I don't want the animals to get upset on the trailer. But if that's the way the police want to go, then I can tolerate 30 seconds. But it must be no more than 30 seconds, and we don't want them filming drivers."

Mr Lutkin also questioned what laws had changed to spark a change in policing.

"We've got video footage of 12 months ago when they were pulling the protesters out of the line of the traffic and putting them on the side of the road, and we've now got a situation where they are allowing them to stop," he said.

Insp Marie Reavey of Norfolk police, who oversees the policing of the protests, said the change followed a landmark legal ruling last year, which balanced potential highways offences against the freedom to protest guaranteed by the European Convention on Human Rights (ECHR).

The Supreme Court ruled that ECHR protections could extend to protests which involve "intentional disruption obstructing others" - but the extent of that disruption was an important factor in determining a "proportionate" police response.

"We always try to police with fairness and proportionality," said Insp Reavey.

"The protesters do have a right to protest under the European Convention on Human Rights, and there was a bit of case law last June which basically says that any disruption caused by protesters obstructing the highway has to be more than 'minimal'.

"That is very subjective, and it depends on the circumstances of the road and the level of disruption being caused. So that is part of the reason it is a challenge.

"Ultimately it is down to the officers on the day, faced with the circumstances they have got, to make that decision.

"In relation to the 30 seconds, there is no set time limit as such, but we will tolerate 30 seconds and then we ask them to move on and they do.

"There is a lot of engagement going on to try and problem-solve this, to work with all parties to come to an amicable situation where all parties are able to go about their lawful rights in a peaceful manner.

"If we have identified offences, and we have got the evidence, then we will deal with those offences fairly and proportionately."

One of the organisers of the Norwich Livestock Market Animal Vigils, who did not wish to be named but is known online as The Active Vegan, said: “We are a peaceful group and all we are interested in is bearing witness to the animals going into the market, and taking footage of the animals which we can share on social media.

“A lot of things are being misconstrued. We stop the vehicles for less time than if you were stopping at a traffic light. Everyone is entitled to film in a public place and to be fair we are also being constantly filmed by the market.

“But we categorically do not intimidate or harass the farmers. The only people threatened here are us, when they drive their vehicles at us in the road so we have to run backwards. So obviously tensions are quite fraught.”