Two horses were attacked on Monday night in a paddock near Coupar Angus, north west of Dundee.

Last week, two horses had their tails partially cut near Aberdeen and in an earlier attack one horse suffered spinal injuries.

It is thought such attacks may increase in the run up to Halloween.

The horses' tails were cut

The claims have angered pagan groups who deny involvement.

The National Equine Welfare Council said its research had established a link between attacks on horses and dates in the pagan calendar.

After attacks in Nottinghamshire last year, possible links with witchcraft were investigated.

It is thought the incidents matched dates in the pagan calendar between October and Easter. After Easter the attacks stopped.

Tails hacked

Now there are fears horses are being targeted again.

Almost a fortnight ago two horses had their tails hacked off with a blunt instrument in a field near Laurencekirk, south of Aberdeen.

Treating a victim of an earlier attack

A few days later two horses owned by Jackie Boyd were targeted in a field on the outskirts of Aberdeen, with significant chunks of hair being removed from their tails.

Ms Boyd said she was "horrified" by suggestions of a link to witchcraft.

"Somebody had said to me last week that it was possibly for rocking horse hair, that was why the tails had been taken," she said.

"That is bad enough, but if somebody was using it for other purposes that to me is just really scary."

Animal welfare groups said the signs to look for are:

• blood being taken
• sticky plaits woven into the horse's mane
• sexual assault
• tails and manes being trimmed

Horse owners and farmers are also being told to watch for small "altars" where horse hair has been burned and symbols such as pentagrams or double headed axes.

The Scottish Society for the Prevention of Cruelty to Animals is appealing for information from members of the public on any such attacks.

They said their inspectors can investigate any such cases that involve cruelty.

Further information is available from the Scottish SPCA on 0131 338 5605 or from the National Equine Welfare Council on: 01295 810060.

BBC News Online has received several e-mails criticising the publication of this article, linking witches, pagans and heathens with the attacks.

The president of the Glasgow University Pagan Society wrote: "We are appalled that we have been implicated in this vile act against horses and even more appalled that the BBC have chosen to report our faith in as bad a light as they possibly can.

"We do not harm animals or human beings. On the contrary, we feel it is our duty to protect this planet and all the creatures that we share it with."