Visitors and volunteers at Heeley City Farm in Heeley have been left horror-struck by the stomach churning attack, in which all 13 tiny piglets were butchered.

Farm spokeswoman Jill Brookes believes the sick killers clambered over a fence before making their way into a sty where the slaughter took place.

Parts of the dead baby animals were then scattered around the farm.

The piglets had been born only hours before their murder to sow Nelly, a Large Black breed of pig.

In 1995, the farm was gutted by a blaze which killed two horses and a donkey. More than £75,000 was raised by local people to rebuild the centre.

Jill said: "The piglets were just a day old.

"We found bits and pieces of three of their tiny bodies scattered around the farmyard.

"At first we thought it might be an animal - a fox or possibly a dog - that had slaughtered them.

"But when we examined the remains of the pigs we found it was obvious humans were responsible.

"One of the pigs had been decapitated and another chopped clean in half, as though they had been hit with an axe or a machete, or possibly a shovel.

"I have worked at Heeley City Farm for 18 years and have never known anything like this.

"It was a vile act and whoever carried it out is quite definitely sick in the head."

Regular visitors to the farm have been left numb by the news.

One woman, who took her three-year-old daughter to see the newborns on the day of their birth, was devastated to learn the piglets had been killed.

She said: "I visited the farm with my little girl and we were delighted to find that the baby pigs had been born that very morning. Everyone was so proud and happy - it really moved us.

"My little girl was so excited we decided to go back, only to be told the terrible news.

"Everyone at the farm is completely shattered. I just can't believe anyone would be so very cruel."

Police patrols have been stepped up in the area. Anyone with information is asked to contact Woodseats Safer Neighbourhood Team on 0114 296 3680.