London Zoo's newborn Sumatran tiger cub has drowned, the zoo has confirmed.
Five-year-old Sumatran tiger Melati gave birth to the cub on 22 September after a six-minute labour. The cub was the first tiger to be born at the zoo for 17 years.
On Saturday, zookeepers could not see the cub on the den cameras and its body was later discovered on the edge of a pool inside the enclosure.
A post-mortem test conducted on Sunday confirmed the cub had drowned.
It is thought that Melati carried the cub outside the den, but keepers are unclear as to how the cub got into the pool as there are no cameras in the wider enclosure.
The cub was born six months after the opening of the "tiger territory", designed to encourage the endangered sub-species of tiger to breed.
Melati's pregnancy lasted 105 days and was kept secret by zookeepers, who maintained a careful watch on the first-time mother through hidden cameras so they would not disturb her.
The cub - which had not yet been named or sexed as it was so young - was the "grandchild" of the zoo's last tiger cub, Hari, the father of Melati.
London Zoo's 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."
He added: "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."