It was thought that sunstroke, caused by soaring temperatures in Edinburgh at the time, might have been to blame.

But the findings of the investigation into the death of the children's favourite have disproved the theory.

A spokesman for Edinburgh Zoo moved to reassure animal rights campaigners that everything possible had been done for Alanis before and after she became ill.

The E.coli bug proved fatal

Keepers were especially vigilant during spells of hot weather, he said.

"The final results of the post-mortem investigation into the death of the baby hippo reveal that she died of E.coli infection.

"These results make it absolutely clear that she did not die of sunstroke. There was no question of any negligence on their part," he stated.

"Alanis was treated by the vet with antibiotics and fluids, and nothing more could have been done to save her.

"We are all very saddened by her death as an individual and for the blow her death has meant to the international conservation breeding programme for this threatened species."