VISITORS and animal welfare experts have criticised Edinburgh Zoo for its "heartbreaking" treatment of one of the world's most endangered animals.

Seven-year-old Amur leopard Skodje – one of only 200 left in the world – is the subject of complaints that he is constantly pacing an enclosure measuring only 20ft wide and 30ft deep.

The big cat arrived at the zoo almost six years ago and was put in the enclosure as a "temporary" measure while a new home was built at the Highland Wildlife Park near Aviemore.

Critics of the zoo say there is still no sign of the new home being completed and Skodje's pacing is a classic sign of distress.

Amur leopards would normally roam areas of Siberia ranging in size from 19 to 120 square miles.

There are thought to be as few as 14-20 adults left in the wild and 176 in captivity.

Visitors to the zoo have left online comments criticising the institution over the size of Skodje's enclosure, which he has shared with female Zane since 2009.

One visitor from Dundee described Skodje "pacing the box, tracing its own footsteps, while being stared at by us humans. It was heartbreaking".

A spokesman for the zoo said its keepers are committed to ensuring its animals' wellbeing "and contribute to this by carrying out extensive animal enrichment to ensure they are stimulated".