A whale found stranded off the coast of Seasalter has been confirmed as dead.

Coastguard crews and marine experts were called in after a sighting of the 20ft mammal in the Swale between Whitstable and Sheppey.

But a spokesman for the British Divers Marine Life Rescue today said the whale had died.

She said: "It has now floated away again as the tide has come in.

"We don't know when it died, or how it died, but it is dead.

"The coastguard will return to search for it when the tide goes back out.

"After that, the zoological society from London will come down and take samples."

Faversham tour guide Mark Roser spotted the huge mammal - now confirmed as a sperm whale - this morning.

Emergency crews were called to the scene, together with the team from British Divers Marine Life Rescue.

Mr Roser, who works for Brogdale Collections, said: "I was walking at Oare marshes and saw this blob on the horizon and I thought 'that's not normally there'.

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"I used my telescope and could see this bulky animal. I think it was around 20ft. It doesn't look like a fin whale as far as I know, but I'm not sure of what sort of whale it is.

"I first picked it up around 8.15am.

"It was certainly stranded and as far as I could see, there was no movement or life.

"It's 2km from the sea wall bird-hide at Oare and nearer to the Sheppey bank on Horsesands.

"I think it would be more accessible from the Sheppey side".

Faversham fisherman Bluey thinks it is plausible for a whale to enter the Swale.

He said: "I’ve not seen one and my fellow fisherman Julian has been fishing a lot this week and he hasn't mentioned anything.

“But there are a lot of herrings and seals in the water at the moment and that is what the whales feed on, so it is a possibility.

“We do get some strange creatures now and again.

“We have seen small whales and porpoises out there before. Obviously not giant blue whales, but we have seen them.”

But the sighting today wouldn't be the first in recent years for Kent.

In 2006, rescuers worked around the clock to try and lead a distressed bottlenose whale to deeper waters after it was spotted in the Thames Estuary off Gravesend.

But the 29-hour rescue attempt involving medics, police and The Port of London Authority ended in heartbreak when the 18ft mammal died.

Then, in 2009, a humpback whale was washed up near Dartford in the River Thames - and was thought to have died from starvation.

Then last year, a dead whale was spotted floating in the Thames Estuary near the Isle of Sheppey.