Britain's only female giant panda is believed to have suffered a miscarriage, Edinburgh Zoo said on Tuesday.

It was a doubly sad day for British zoos, after London Zoo also announced Tuesday that the first tiger cub born there in 17 years had drowned.

Edinburgh said its panda Tian Tian, who is spending a decade in the Scottish capital on loan from China with her male companion Yang Guang, had been displaying all the signs of pregnancy but is now thought to have lost her cub.

"Experts at the Royal Zoological Society of Scotland can now confirm that they no longer believe Edinburgh Zoo's female giant panda, Tian Tian, is pregnant," the zoo said in a statement.

"All of her hormonal and behavioural signs now indicate that she had conceived and carried a foetus until late term, but then lost it."

Hopes had been high that Tian Tian was about to give birth to Britain's first ever panda cub after the zoo said in August that she was showing signs of pregnancy, including a lack of appetite, moodiness, and changes in her hormone levels.

"We are all saddened by this turn of events after so many weeks of waiting," said Chris West, CEO of the Royal Zoological Society of Scotland.

"The panda enclosure will remain closed until the end of the week, in order to give Tian Tian time to get back into her routine and provide her keepers with the chance to recuperate after this long period of waiting."

Tian Tian ("Sweetie") was artificially inseminated in April after repeated attempts to make her mate with Yang Guang ("Sunshine").

Pandas are famously disinterested in sex for most of the year, and when they do couple they must adopt a very precise position in order to mate successfully.

Edinburgh is paying around $1 million (750,000 euros) a year to Chinese authorities for Tian Tian and Yang Guang -- the only pair of giant pandas in Britain -- who arrived in 2011.

Fewer than 1,600 pandas remain in the wild, mainly in China's Sichuan province, with a further 300 in captivity around the world.

At London Zoo, meanwhile, keepers were "distraught" after finding its newborn Sumatran tiger cub dead at the edge of a pool inside its enclosure.

The zoo said the unnamed cub -- which was born just two weeks ago -- had been discovered on Saturday morning.