Argentina's last polar bear, Arturo, has died aged 31, officials at the controversial zoo where he lived said Monday.

Arturo was the latest of more than 60 animals to die over recent months at the zoo in the western city of Mendoza.

Other animals were struck down by infections blamed on poor conditions at the zoo, but Arturo's death was linked to old age.

Environmentalists had campaigned for years for him to be transferred to a zoo in Canada.

Arturo died on Sunday "due to a blood circulation imbalance" which caused a general decline in the bear who was already weak due to old age, the zoo said in a statement.

The Mendoza zoo was closed to visitors last month after 64 animals died between December and May. Officials said outbreaks of bacteria and overcrowding were to blame.

The city hall said it was planning to convert the zoo into a nature reserve and send the animals to more suitable conservation sites.

Arturo was brought to Argentina from the United States 23 years ago. 

"We hope that he will be the last polar bear to be held in a zoo in our country and that his case will oblige the authorities to review the state of other exotic species still living in the same situation," Greenpeace spokeswoman Soledad Sede said in a statement.

Environmental groups in 2012 launched a campaign for Arturo to be transferred to colder climes in Canada.

They described him as "the saddest bear in the world" after the death of his female partner at the zoo.

Veterinarians at the time judged however that Arturo was too weak to survive the journey.