Two people were arrested following angry confrontations between cattle farmers and vegan protesters at Norwich Livestock Market.
Animal rights activists have been holding regular 'vigils' at the Hall Road market for the last five years, and now attend every fortnightly sale.
In recent months, Norfolk police officers have permitted protesters to stop livestock trucks on the access road for 30 seconds, filming and photographing their animal occupants.
But during a particularly busy sale day on Saturday - including a record entry of around 500 cattle and calves - tempers flared and police made two arrests, one farmer and one protester.
Market chairman Stephen Lutkin said although regular discussions were held between the market directors, protesters and police to ensure peaceful protests, confrontations and arrests were not uncommon.
He said: "Everyone has their right to protest - that is fair enough, and I don't have a problem with that.
"But it is getting a bit more aggressive and you get flashpoints at every market.
"For a lot of farmers this is a social event, but the first thing they are greeted with is a group of protesters who will stand in front of your motor, many will cover their faces so you only see their eyes, and they stare you out, take pictures of you.
"It is intimidation and harassment.
"I've got no problem with them protesting, but in my opinion they are protesting against the wrong people.
"This is the biggest entry of cattle we have ever had since we started up 20 years ago. The reason for that is because of the prices, and the demand for the meat.
"If they want to protest, they should protest with the end user, which is the people buying it. If people didn't want the product, we wouldn't be supplying them."
Although the protesters were approached and asked to comment, they declined.
But the Norwich Livestock Market Animal Vigils Facebook page says the group aims to "bear witness" to the treatment of farm livestock, and "expose the reality of animal agriculture and enlighten others of their plight".
It adds: "Our vigils are peaceful and criminal conduct will not be tolerated. We work hard at getting agreements in place between farmers, slaughterhouse and police and unwanted actions can jeopardise these."
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