Hong Kong (CNN) -- The first giant panda to be born in Japan in 24 years has died just one week after generating huge excitement in the country as locals celebrated the rare birth.
The seven-day-old unnamed cub died from pneumonia after its mother's milk accidentally entered its airway, according to officials at Tokyo's Ueno Zoo, where it was born.
Toshimitsu Doi, the head of the zoo, told reporters at a televised press conference that the baby panda was found not breathing on its mother's belly.
It had been returned on Tuesday to its mother's cage from an incubator, and zookeepers had heard its cries at 6:45 a.m. on Wednesday. Less than an hour later, they discovered the lifeless cub and tried to revive it by massaging its heart. The baby panda was confirmed dead at 8:30 a.m. local time.
"The cub swallowed milk into its respiratory organs and developed pneumonia," Doi said, while wiping away tears.
The seven-year-old mother, Shin Shin, had given birth to the baby after conceiving naturally, a first in Japan and a rare feat among the bears who have a low birth rate and are usually bred in zoos using artificial insemination.
The cub was celebrated by the zoo as a success of its breeding program, and officials held daily press conferences since its birth last Thursday to report on its development.
The cub was monitored around the clock and was occasionally placed in an incubator.
Zoo officials said at the press conference that 60% to 70% of baby giant pandas die within their first week.
China leased the mother, Shin Shin, and her mate, Ri Ri, to Japan in early 2011 for a fee of $1 million per year.
China is known to use gifts or loans of pandas as gestures of diplomacy. After the cub's birth, a spokesman at the Chinese foreign ministry said the newborn could promote better relations between China and Japan.
Shortly before the cub was born, Shintaro Ishihara, the governor of Tokyo, sparked outrage in China by suggesting the cub be named "Sen Sen" or "Kaku Kaku" -- both in reference to Senkaku, the Japanese name of disputed islands lying 120 miles east of Taiwan that are a prominent source of tension between the two countries.
In 2010, a 14-year-old panda under loan by Japan died while under anesthesia during a semen-extraction procedure. Its death worsened the strained relations between China and Japan at the time over the islands, which are called Diaoyu in Chinese.