Roxane Hobbs, who runs Beaconsfield Stud at Gunby, keeps horses in Burgh, near the Bridge chip shop, during the summer, and in a field in Bratoft during the winter.


For about a year, she has been called out regularly because her horses have been loose in both Burgh and Bratoft.


She was called out again on Wednesday morning by a Burgh resident who showed her the field gate had been wedged open.


Miss Hobbs said: "They've been out before but I thought the ponies had found a weak spot in the fence.


"Now I'm definitely sure they've been let out deliberately. Somebody is conducting a campaign against me by letting these ponies out."


Miss Hobbs has been forced to travel miles, day and night, trying to collect up to 10 ponies up at a time when they get out of their fields.


She said: "Touch wood, nobody has been injured so far, but if people keep letting them out surely it's only a matter of time before a person or pony is injured or killed?"


The busy bypass is not far from the Burgh field and MIss Hobbs is terrified about what could happen if the ponies wander into the road.


The Burgh field is a public right of way so Miss Hobbs cannot chain the gates. She does not believe people are leaving them open by accident because it is obvious the ponies are there.


PC Stan Standbrook said: "We have every sympathy with Mrs Hobbs and share her concerns about the safety of her horses.


"Equally, we have concerns about the safety of road users in the area, particularly those travelling along the A158."


He reminded people using the public right of way to ensure the gate is kept bolted.


He said: "Leaving it insecure is irresponsible and potentially very dangerous for the horses and road users that could lead to very tragic consequences.


"If the gate has been deliberately left open, then we would encourage witnesses to come forward and provide us with any information they have about who they believe could be responsible."


* Information to: Horncastle Police Station, tel 01507 523332, or Crimestoppers anonymously, tel 0800 555111.