Anti-union hardliners cut a Tayside farmer’s phone lines twice and threatened to release livestock on to a road.
The “sinister” incidents, at two separate farms, have been reported to Police Scotland amid claims anonymous callers are harassing farmers who display No Thanks banners.
Mid Scotland and Fife MSP Liz Smith contacted Chief Constable Sir Stephen House to request an investigation, following complaints from several landowners in the corridor between Dundee and Perth.
The Perthshire farmer whose phone lines were cut said a series of his signs had also been defaced.
He added: “Twice they cut the main lines leading from the road into the estate. The police are now dealing with the matter. It made me very cross.”
The move comes after No banners were damaged in the Stirling area over the weekend, adding to scores of vandalised signs across Scotland in the last few weeks.
Some were torn or knocked down while others were spray painted with the words ‘traitor’ or ‘traitor watch’.
Ms Smith claimed the intimidation of the farming community marked a new low in the referendum campaign.
“These farmers have received anonymous messages and calls ordering them to take down their signs and making it very clear that if they do not do so their farm gates will be broken so that their livestock can wander freely across roads and local village communities,” she said.
“This is wilful, organised intimidation and it is clearly a matter for the police and that is why I have written to Sir Stephen.
“Whether people choose to support No or Yes in this referendum is entirely a matter for the individual and they should be free to express that view without any fear of this repugnant behaviour.”
A second Perthshire landowner, who asked not to be named, called the police at the weekend when two banners were ripped down and burned, one with “scum” daubed across it.
He said: “It makes you ashamed to be Scottish it’s the first time in my life I’ve felt that way.”
Another farmer, who has land near Arbroath, had boxes and a trailer sprayed with ‘Yes’ and ‘Freedom’.
“I don’t want to give my name because you just don’t know what they might do next,” he said.
A spokeswoman for the National Farmers’ Union Scotland said they had not received any direct reports of intimidation but were aware of vandalism to signs.
She added: “The campaign is now heating up as it gets into its final days and there can often be quite an emotionalargument put forward.
“We wouldn’t encourage this kind of behaviour and would advise any farmers who feel threatened to report the matter to the police.”
Assistant Chief Constable Bernard Higgins said officers will “respond appropriately” to any issues which arise as the vote draws nearer.
He added: “The referendum is a significant event which is expected to attract a higher than normal turnout.
“Policing arrangements for the referendum are well in hand and will be appropriate and proportionate.
“Police Scotland’s priority is to ensure public safety and security.
“We will not offer comment on the numbers of officers or their specific operational deployment.”