image copyrightTokyo Zoological Park Societyimage captionThe twins were born on Wednesday at Tokyo's Ueno Zoo

A giant panda has given birth to twin cubs at a Japanese zoo.

Shin Shin gave birth to the cubs on Wednesday, Tokyo's Ueno Zoo announced. It is the first panda birth there in four years.

The sex of the cubs has not yet been revealed.

Giant pandas are notoriously difficult to breed in both the wild and in captivity. Only a few thousand of them remain, with conservationists classifying them as vulnerable.

Ueno Zoo director Yutaka Fukuda said it was the first time panda twins had been born there.

"When I heard the news that the second baby was born, I couldn't help but whoop," he told reporters.

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Giant pandas rarely take care of two cubs at the same time, so the zoo has decided to put one of the animals into an incubator.

"We will be making sure the mother panda will breastfeed one while we keep the other in the incubator," a spokesperson for the zoo, Naoya Ohashi, said.

image copyrightAFPimage captionStaff at the zoo suspected Shin Shin could be pregnant after she mated with her partner Ri Ri in March

The cubs will be swapped over so that they can both "experience natural feeding," he added.

Staff at the zoo suspected that 15-year-old Shin Shin could be pregnant after she mated with her partner Ri Ri in March. The pregnancy was confirmed several weeks ago.

News of the potential pregnancy caused the share prices of restaurant chains close to the zoo to temporarily surge. Pandas play a powerful role in Japan's tourism economy, and share prices rise as investors are encouraged by the possibility of more zoo visitors.

Both Shin Shin and Ri Ri are on loan from China, and had a cub named Xiang Xiang in 2017. They had another cub in 2012 – the first panda born at the zoo in 24 years – but it died after just six days.

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