Indonesian officials are investigating the mysterious death of an African lion found hanged in his own cage in Indonesia's "zoo of death", where a number of animals have perished due to neglect, starvation and mistreatment in the past few years.

The 18-month-old lion was found suspended from the roof by steel cables on Tuesday in Surabaya zoo, east Java, where the eighth animal to die at the zoo in the last 10 months.

Agus Supangkat, a spokesman for the zoo, denied any wrongdoing and said the lion, called Michael, must have caught himself accidentally in between the cables.

"Michael was relatively young – he was only one and a half years old," he told the Jakarta Globe. "It could be that he was playing around and somehow his head got stuck."

But forestry minister Zulkifli Hasan ruled out an accidental death and said there would need to be an investigation.

"We want the perpetrator arrested. The death of the lion seems to have been caused intentionally," he was quoted as saying by the national news agency Antara.

Police are investigating the cause of Michael's death but initial efforts were hampered after it was discovered the lion's body had been cut down before officials could inspect the cage.

Surabaya zoo was built under Dutch colonial rule and is home to about 3,500 creatures, including African lions, elephants and capuchin monkeys.

But a number of animals have died there in recent years, among them a Sumatran tiger who ate meat laced with formaldehyde and a giraffe that had an 18kg ball of plastic in its stomach – the result of consuming plastic wrappers discarded in its cage by visitors. In 2010, it was estimated that about 25 animals at Surabaya zoo were dying prematurely every month.

Michael's death this week followed that of a wildebeest just two days earlier, who was found dead from stomach problems.

Conservationists point to a lack of animal welfare at the zoo and have raised concerns over possible staff involvement in illegal wildlife trafficking.

Rosek Nursahid, the director of animal charity group Pro Fauna Indonesia, told local media that mismanagement at the zoo was to blame and warned that tourists would be boycotting the zoo and city in protest at the animals' treatment.

An online petition has requested the government to close the zoo, but no other facility has apparently offered to take on the remaining animals.