Campaigners are desperate to free an elderly brown bear who has been dubbed the "world's saddest" having spent his entire life in captivity.

Nelson, who is blind, has spent years in a small, filthy cage and barely receives any food or water, claims International Animal Rescue (IAR).

He has broken his teeth on the bars containing him and worn down the floor of his enclosure from pacing up and down, the group said.

Two years ago Nelson is understood to have lost his sight and has also developed arthritis, reports the Daily Star.

Locals claim his captors in Armenia subject him to constant neglect and often leave him to starve for days before finally barely giving him enough nutrition to survive.

Nelson has spent years in a small, filthy cage and barely receives any food or water, it is claimed
The brown bear lives in a tiny cage

Alan Knight, Chief Executive of IAR, said: "This poor bear has served a 30-year life sentence behind bars.

"He has suffered the mental and physical torture of a lifetime locked up in a small, barren cage with nothing to amuse or distract him.

"He has paced round and round for so long that he has worn a track on the floor.

Nelson has spent years in a small, filthy cage and barely receives any food or water, it is claimed
He is said to often goes days without being fed

"His teeth are broken from gnawing on the bars of the cage. And about two years ago, the poor animal went blind. He is in pain from arthritis and now also lives in darkness."

Pressure to free Nelson is mounting from UK-based charity IAR and its partners in Armenia, the Foundation for the Preservation of Wildlife and Cultural Assets (FPWC).

In a statement released on Monday, IAR said it wants the Armenian government to force Armen Tadevosyan - the bear’s captor – to surrender him.

Nelson has spent years in a small, filthy cage and barely receives any food or water, it is claimed
Campaigners are desperate to have him freed

Mr Knight continued: "The bear’s life sentence must not be allowed to become a death sentence. There is still time for him to know kindness and compassion.

"We’re calling on the Armenian government to show clemency to this bear by allowing us to rescue him while there is still time. His 'owner' claims to love the bear but loving an animal means taking proper care of it and feeding it, not letting it live in squalor and neglect."

In 2017 the IAR and FPWC teamed up to launch The Great Bear Rescue with the ambition of rehoming all caged bears in Armenia.

According to the statement, the coalition has freed 30 bears but still suspects up to 50 more in need of help.

Ruben Khachatryan, Founder and Director of FPWC, said: "We urgently need the government’s go-ahead to rescue this poor old bear so that it can spend its remaining years in our care.

"Shame on the man who has allowed him to live for 30 years in such a shocking state.

"He must surely be the world’s saddest bear, to have lived in pain and darkness for such a very long time. Once the government is aware of this case, it can’t turn its back on the animal’s suffering."

Mr Khachatryan added that the charities will do everything they can to make Nelson's retirement a happy one.

He said: "With the government’s support, we can move this bear to our Wildlife Rescue Centre where our rescued bears are well cared for and learn to enjoy life after years of misery.

"Our vet will treat his ailments and we can even find out whether his sight could be restored.

"The people of Armenia will be horrified that an animal is being kept in such appalling conditions and I know will join us in calling on the government to act immediately to save him."