They have formed a group called Poacher Watch to fight poaching, but say their regular patrols are not enough.

Farmer Mark Leggett of the Boston district hare group, who regularly patrols an area north of Boston for illegal hare coursers, says: "We need higher fines and more power to take their vehicles away from them."

Mr Leggett says as many as 30 vehicles are involved in illegal hare coursing in his area on some weekends.

'Thinly stretched'

"We try to avoid confrontation, but even a polite request for people to leave the land can lead to a fist in the face or a brick through the car windscreen," Mr Leggett said.

"When they see us filming, they will ram our vehicles or try to force us off the road."

Dogs are used to chase and kill hares

The members of the hare group contact the police regularly when they go looking for instances of illegal hare coursing, using video cameras to collect evidence.

"We understand how thinly stretched the police are, but it would be nice to think the Lincolnshire police were adequately staffed to do this work themselves."

Asked by BBC Radio Lincolnshire whether he was afraid of the hare coursers, he said: "It takes a strong will to stand up to these people.

"I have seen them driving over my crops with seven four-wheel drive vehicles at one time."

Anyone caught hare coursing can be fined up to £200.