The death of the much-loved hippopotamus Gustavito at the National Zoo of El Salvador was due to poor health care, not stabbing, a post-mortem report has revealed.

The development comes after zoo authorities earlier said that the 15-year-old animal had been stabbed and beaten by unknown attackers, who were believed to have sneaked into the zoo at night over the weekend and brutally assaulted the animal with sharp weapons and blunt tools. However, state prosecutor Mario Salazar said that they found no sign of puncture wounds on the hippo that died last Sunday (26 February).

The post-mortem suggested that the animal died of a pulmonary haemorrhage, or bleeding from the lung.

However, Culture Minister Silvia Elena Regalado said the post-mortem examination did not exclude an attack on the hippo, which she said could have died from the resulting stress.

On 25 February, the zoo's veterinarians found lacerations on Gustavito's neck and face, and the animal was in great distress. He even refused to eat and showed unwillingness to come out of the pool in his enclosure

However, his condition worsened on Sunday and he died late that night despite the efforts of the staff to save him, the BBC reported.

The alleged attack on Gustavito caused worldwide outrage and the zoo officials described it as cowardly and inhumane, which resulted into the investigation by police, who questioned each and every staff at the zoo to find out who could have entered the premises to carry out such an attack.