A landowner has blocked part of a footpath using bales and a van "to stop coronavirus".
Farmer Nathan Michell said walkers touching gateposts and crossing on the narrow path increased the risk of spreading the virus.
The Engine House trail runs from Truro to Hayle in Cornwall and is used by walkers, cyclists and horse-riders.
Cornwall Council said it would be working with police to resolve the issue.
The Local Democracy Reporting Service reported a van had been parked across the path at Carharrack, near Redruth, and wrapped hay bales had been put in in front of the gates further along.
Mr Michell told the BBC the bales had been slashed by people angry at the closure of the path.
He said: "People are walking up and down this path that is not 2m wide.
"I needed to close the path off to stop coronavirus.
"It's ludicrous with this virus and people supposed to keep 2m apart."
Mr Michell said he had tried to keep gates used by him and his staff disinfected but it was an impossible task with people constantly using the path.
The beef farmer, whose farm is either side of the trail, said he emailed Cornwall Council to tell them about his plans.
He said he did not receive a response but police and council officers visited him at his farm on Saturday to discuss the closure.
Mr Michell said the path, which he believes is a public bridleway, would be reopened "when safe to do so".
A man who runs to work along the trail, who did not want to be named, said: "It is completely blocked, you can't get through there.
"Now I have to use the road for a mile or more instead of using the trail."
Cornwall Council's countryside access team said in a statement: "We are aware of obstructions on part of the Engine House Trail just outside of Carharrack.
"We are working with the police to resolve this issue."