The female was walking two liver-coloured German pointer dogs along Newbarn Lane off their leads.

One of the dogs was seen to run into a field occupied by a flock of sheep.

The dog was seen to attack a number of the animals. One of the adult ewes died as a result of its injuries. Some new born lambs received minor injuries.

It is believed a number of local residents saw the dog run into the field after the sheep.

PC Stuart Bethan, of Bognor Regis police station, said: "This was clearly a particularly upsetting incident for the owner of the sheep as well as for local residents who witnessed part of the incident.

"The fact that one of the sheep has died and a number of new born lambs received minor injuries does raise significant concern that this could happen again in the future unless measures are taken to ensure it doesn't."

The attack happened at about 3.15pm on April 30.

The dog walker has been described as white, in her late 40s and of medium to heavy build.

She had short dark hair and wore a blue sleeveless padded jacket. It is believed she had dog whistles on a strap around her neck.

She was seen to walk her dogs away from the scene of the attack towards Chalcraft Lane.

PC Bethan said anyone who recognised the woman should contact him on 0845 60 70 999.