London Zoo keepers have been left heartbroken after the first tiger to be born there in 17 years died.
The two-week-old cub was found on the edge of the pool inside the tigers’ enclosure on Saturday morning.
A post-mortem examination on Sunday confirmed the cub had drowned, a ZSL London Zoo spokesman said.
"The keepers are naturally very distraught. They work very closely with the tigers, so it is incredibly sad news for them," she said.
After a pregnancy lasting approximately 105 days and a six-minute labour, five-year-old Sumatran tiger Melati gave birth to the cub at 9:22pm on Sunday 22 September.
The happy event was captured on hidden cameras, installed to keep watch on Melati without disturbing her.
Born exactly six months after the opening of the brand new Tiger Territory exhibit, opened by Prince Philip in March and designed specifically to encourage breeding of this critically endangered and declining sub-species, the tiger keepers were thrilled with the new arrival.
It is thought that Melati carried the cub outside but keepers are unclear as to how the cub got into the pool as there are no cameras in the wider enclosure.
Keepers are reviewing the situation as it was not envisaged that the mother would take the cub outside so early.
Curator Malcolm Fitzpatrick said: "We're heartbroken by what's happened. To go from the excitement of the birth to this in three weeks is just devastating.
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"Melati can be a very nervous animal and we didn't want to risk putting her on edge by changing her surroundings or routines, in case she abandoned or attacked the cub.
"At the time we thought it was in the best interests of Melati and her cub to allow her continued access to the full enclosure as normal.
"We would do anything to turn back the clock, and nobody could be more upset about what's happened than the keepers who work with the tigers every day.
"They are devoted to those tigers and are distraught."
The cub was the grandchild of the zoo's last tiger cub, Hari, the father of Melati.
The cub's father is five-year-old Jae Jae, which had been playing no part in taking care of the new arrival.
There are only 300 Sumatran tigers left in the wild and their habitat is being lost to the manufacture of palm oil.