Animal rights activists Wednesday demanded the closure of an Indonesian zoo after skeletal sun bears were pictured begging for food from visitors and eating their own dung.

The bears at the zoo in the city of Bandung were shown waving their arms in the air inside their enclosure -- with their ribs visible through their fur -- as people hurled food at them.

In one video, a bear defecates in the enclosure and then eats its own faeces.

Many of Indonesia's zoos are poorly maintained and there are regular reports of animals dying in captivity. Bandung zoo came under fire last year after the death of a critically endangered Sumatran elephant.

The Scorpion Wildlife Trade Monitoring Group, which shot videos of the bears last year, said it now wanted the zoo closed down.

"The bears ate their own dung, this happened because they are very, very hungry," Gunung Gea, director of the Indonesian group, told AFP.

"The enclosure of the bears was dirty, and visitors were free to give them whatever they wanted -- they were throwing in junk food."

Scorpion investigators first raised the alarm after visits in 2016. During a follow-up visit this month, they found there were still "dirty enclosures" and bears "looking hungry", the group said.

An online petition set up by Scorpion protesting the bears' treatment has gathered over 3,000 signatures, and the group has also staged protests calling for the zoo's closure.

However Bandung zoo spokesman Sudaryo, who like many Indonesians goes by one name, denied the bears had been badly treated or were malnourished.

"We give them food daily, twice a day," he said. "That means the management has done its duty."

Indonesia’s most notorious zoo, in the city of Surabaya, has been dubbed the "death zoo" as hundreds of animals have perished there in recent years.

The sun bear, also known as the honey bear due its love of honey, is the smallest of the bear species and inhabits Southeast Asian tropical forests and swamps.