A reward of £100 has been offered after two swans were killed in a sickening attack in Brooklands Lake, Dartford.

A cygnet was found decapitated and its mother later died from its severe injuries.

Members of the animal group South Norwood Animal Rescue and Liberty (Snarl) said: “We were notified and saw the body of the swan earlier this afternoon. Unfortunately the body of the cygnet has not yet been recovered.”

It is understood a man spotted the injured swan and waded into the lake to save it. But it died on its way to a vet. There is a male swan and four other cygnets still on the lake.

A Snarl spokesman added: “It was deeply upsetting to see such a beautiful bird, which had been in such good condition, dead.

“She wasn't killed for food or out of need. She was killed for fun - and that is despicable. We would urge anyone who knows anything about this incident to contact the police on 101.”

There is a £100 reward for information leading to the conviction of the swans' attackers.

The spokesman said: “We’d like to thank Mead vets in Dartford for not only taking the body in but also giving us a chance to look at her.”

Snarl believes the killings on Thursday could be linked to the death of a cat from Joyden's Wood.

Snarl added: “We salute the quiet courage of the man who waded into a lake to try to save the mum.”

A similar attack on swans was reported in Gravesend recently.