Police are searching for a man who stood by and watched his three 'out of control' pets kill a young swan in a quiet park near Norwich.

The dogs 'tore apart' the cygnet, which was less than a year old, at Whitlingham Country Park in Trowse on Sunday.

The owner was seen walking with two greyhounds and a Doberman in the park at about 11am on Sunday.

All of the dogs were off their leads and only one was wearing a muzzle.

Witnesses described how the dogs seemed out of control and ran to a lake where they 'tore apart' the swan as their owner stood by.

They caused such severe injuries to the bird that it had to be put to sleep by a vet after the attack.

Now the RSPCA and the police have launched an investigation in a bid to track down the animals and the man.

RSPCA inspector Emily Bottomley, two police officers and Keith Glen-West of Water Bird Rescue spent three hours trying to rescue the cygnet, which was trapped on ice 12 feet from the bank.

A boat could not launch because of the ice and eventually the swan had to be dragged to shore with poles.

Inspector Bottomley said: 'Once we managed to get the cygnet to the bank we realised just how shocking its injuries were. It had a badly damaged wing and its intestines were hanging out of its body.

'It was so upsetting that, after trying to rescue this poor bird, we could do nothing to help it, the injuries were so severe.

'The swan suffered unimaginable pain and distress throughout its ordeal and it was put through this just because someone did not keep their dogs under control.

'We think the owner must have realised what could happen by allowing his pets to roam around in an area where there are so many wild birds and animals and at the very least he could have prevented this attack from happening,' she added.

PC Mark Campbell said that there were several members of the public in the area at the time and urged them to come forward with information to help bring the owner to justice.

Anyone with information about the attack should call police on 0845 456 4567 or the RSPCA cruelty line on 0300 123 4999.

People who are found to have allowed their dogs to be dangerously out of control in a public place or attack other animals can face up to six months in prison.