POLICE are investigating allegations that an air rifle was fired towards balaclava-clad protesters outside a Brentwood slaughterhouse.

Campaigners, wearing fake blood-stained overalls, pig suits and masks, claim the shots dented the side of a blue BMW 320 hire car, rented by an animal rights activist and parked near the Warley abattoir.

An 18-year-old man was also cautioned for throwing a bottle at a protester as trouble erupted outside the slaughterhouse, owned by Cheale Meats Ltd, in Little Warley Hall Lane.

About a dozen from the Essex Animal Defenders sang and chanted abuse on Wednesday.

Janie Callow, 40, whose hire car was dented, said: "I was very shaky and as another protester ran ahead of me the final shot came and he saw it bounce off the car. He was probably only a second or two away from being shot himself."

She later added: "There have been protests since about August and they have been getting increasingly nasty."

Another protester, who did not want to be identified, said: "There were about four shots and three [pellet] holes in the car."

The police said: "The allegations that an air rifle was discharged are being investigated.

"A search of the area was carried out. No weapons, cartridges or shots were found.

"An 18-year-old man from Dagenham was arrested after a protester was struck by a water bottle. The man, who was a passing motorist, was later issued with a caution."

Since covert footage of two workers abusing pigs, recorded by the campaign group Animal Aid, was broadcast last July, the firm insists it has done all it can to ensure the highest welfare standards. Three workers have been sacked.

However, police have been called to several protests and in September last year a wheelchair-bound protester criticised officers who carried her away from blocking the entrance to the abattoir.

She claims they broke her wheelchair and bruised her legs in the process.

Speaking about Wednesday's protest, Inspector Jon Burgess said: "We were present to ensure a peaceful protest. This escalated and it was a shame resources were diverted from other patrols and incidents."

Cheale Meats Ltd denies any involvement in the incidents on Wednesday.