Tests have revealed that a dead otter, discovered on the bank of the River Dour in Dover, was actually a polecat ferret.

Experts were due to carry out a post-mortem on the porpoise on Monday, but they soon discovered it was a polecat ferret, which is a cross between the two animals.

The animal was thought to have been for three to four weeks, making it difficult to identify.

Peter Nix and his daughters, who live in the Coombe Valley road area, came across the otter in disguise on Sunday afternoon, where they found it limp and lifeless by the Charlton carpark stretch of the river.

Mr Nix's first instinct was that the animal was a large rat, but after closer examination he thought it was an otter.

But experts at the Wildwood Trust, based in Herne Bay, said it was a polecat ferret, not an otter.

Anne Riddell, head of education at Wildwood said: "It was shot in the head.

"It was probably mistaken for a mink, it is the first one I have seen."

The difference between an otter and a ferret is the build, the thickness in fur and the shape of the head.

Mr Nix said: “It looked like an otter so I posted the picture on the Dover for Dovorians site and it was later confirmed it was a female otter.”

Animal rights activist James Roberts also believed it was an otter.

He said: “The otter was located and recovered from the river by animal rescue patrols on Monday.

“The Live Export patrol who recovered it believed it was a disease that took the life of the young female otter."

Sue Proudfoot, owner of Curly Sue’s Edible Plants in Hoath, said: “It was great for the Dover people to come together and act on it. There were lots of people involved, well done Dover.”