Firearms officers and police helicopters have joined the hunt for a lion thought to be roaming loose near Clacton, Essex.

Locals have been warned to stay inside, as search teams worked around the clock to try and track down the big cat, which was photographed in a field on Sunday night.

Experts from Colchester Zoo are among those involved in the search, having confirmed that a photograph taken of the cat seems to be genuine.

The cat was spotted in fields off Earls Hall Drive in St Osyth, near Clacton, Essex, just before 7pm yesterday.

Che Kevlin said he heard what he believed to be a roar whilst out walking his dog last night.

"I heard a loud roar at 10pm. It sounded like a lion," he told the BBC.

"It was worrying as we had just been for a walk with the dog. We saw the police helicopter but thought it was just searching for a person.

"It sounded like the roar of a lion. We have a field and wood just behind our fence, so you never know."

It is not yet sure how the lion came to be loose in the area - Colchester Zoo has accounted for its big cat stock. Rumours that the animal may have come from the Great British Circus, which recently toured the area, have not been substantiated.