Images of a seal that has been so neglected it has become covered in seaweed has led to calls for the zoo it is kept in to be closed.

Animal rights activists want the small zoo in the Magdalena Peninsula, in Santander, closed immediately and have condemned it as a “throwback” to the bad old days.

Images of unhappy animals at the zoo have been circulating on Spanish social media sites and have led to a petition for its closure.

The animal rights group AnimaNaturalis says more than 6,000 have signed its letter of protest to Santander council.

The charity’s leader Aïda Gascón said that the seal covered in green algae “seems to be letting itself die.”

But opposition parties unsuccessfully tabled a motion before the city council demanding to shut the zoo.

Seal covered in seaweed at Santander zoo.

Local councilor Daniel Fernández: “Those pictures convey an image of inconceivable and disgraceful treatment of animals when we see things like the sea lion pen with no water.

“This would be unacceptable anywhere in the world, but it is even more surprising in a city that wants to position itself as a tourist attraction.”

More than 26,000 people have signed an online petition on to close the Magdalena mini-zoo which was built in the 1980s.

Santander Mayor Gema Igual denied the animals were mistreated by the mini-zoo.

Igual, of the conservative Popular Party, said images of a grey seal had been taken out of context.

She said: “That photo was of a sleeping animal and the dead sea lion was not in a place people could see it because it was known to be ill.”