More lambs are being killed by dogs in 2008 than in previous years, according to park rangers and farmers.

Environmental wardens and the Pentlands Hills rangers have been put on high alert and will be carrying out extra patrols after another spate of lamb killings and attacks on pregnant ewes at the weekend.

One dog has been shot this year and over last weekend there were three separate incidents of sheep being attacked and lambs killed in the Pentlands area.

Park rangers have had reports of six separate cases this year where sheep and lambs have been killed or have had to be put down as a result of dog attacks.

Alastair Paisley, vice chairman of the Pentland Hills Regional Park Committee said: "We have seen worrying number of dog attacks on lambs this year - much more than in previous years - and we want to put a stop to it."

Farmer Graham Hamilton, whose sheep were attacked this weekend, said: "This lambing season has been the worst for many years.

"On top of the attacks it seems that a lot of people don't realise that simply letting a dog run near sheep kills unborn lambs."