Dog owners are being warned to be careful when walking their pets as "frustrated" police officers try to crack down on sheep attacks.

This week, a dog attack led to the deaths of 13 sheep in Much Hadham - the worst attack in Hertfordshire for the last three years.

Two dogs were caught chasing a flock of sheep at around 5.30am on Sunday morning and have now been seized, and placed in police care.

Hertfordshire Constabulary recorded 108 incidents of livestock worrying from May 2014 to August 2017.

In that period, 106 livestock were killed and 105 were injured - and in 58 per cent of cases, the dog owner was not present at the time of the attack.

According to insurance firm Lycetts, Hertfordshire farmers suffered a financial loss of £23,470 from killed or maimed sheep.

William Nicholl, of farm insurance specialist Lycetts, is concerned dog owners are not fully aware of the risk their animals may pose to livestock. Lycetts say farmers are forced out of the industry every year due to the trauma and crippling cost of the attacks.

He said: “Unfortunately, even the most docile of dogs can get caught up in an attack on sheep because many of them think it is a game.

“What many dog owners don’t realise is that their dog does not have to physically attack a sheep to cause harm. A barking or ‘playful’ dog may spark blind panic among the flock.

“Even if a dog does not make contact with the livestock, the stress from worrying by dogs can cause sheep to die – often by the dozen – and expectant ewes to abort.

“As we are in lambing season, the flock is at its most vulnerable now, and we urge dog owners to take heed and stick to the lead.”