Worried pet owners have called in the police after a dozen terriers were dognapped from neighbouring rural villages.

In every case the pedigree dogs were let out by their owners for exercise and mysteriously vanished.

The area between the three Northumberland villages of Wark, Blanchland and Kiln Pit Hill, has now been dubbed the Tynedale Triangle by worried owners.

The mystery deepened after the unexpected return of two male dogs two weeks after they vanished at the exact spot where they were last seen.

Police believe they are being stolen for breeding purposes.

It appears the well-bred pets were whisked away and left to mate with females before being placed back unharmed.

But the fate of the other ten pets, many of which are female, remains uncertain.

A total of nine Jack Russells, two Lakeland terriers and a Yorkshire terrier have all vanished from family homes in the last three weeks.

A greyhound has also disappeared.

Sisters Julie Medlen and Jackie Dart, who live in neighbouring properties in Blanchland, are frantic with worry after their two dogs disappeared.

Julie said: "They do tend to stay out quite a long time unsupervised, because this is a fairly remote area, but we have never had anything like this before."

Sergeant Eddie Bell, Durham police wildlife liaison officer for the area many of the dogs disappeared from, said yesterday: "I have been made aware that several dogs have been taken in this area.

"We are warning dog owners to take extra care of their pets because this has become a big problem.

"There is a strong possibility the dogs have been taken for breeding.