Panda triplets born in China. How rare are they?

China announced Tuesday the birth of extremely rare panda triplets in a further success for the country's artificial breeding program.

The three cubs were born July 29 in the southern city of Guangzhou, but breeders delayed an announcement until they were sure all three would survive, the official China News Service said.

The mother, Ju Xiao, and the three as-yet-unnamed cubs are healthy, the news agency said. Photos showed the three sleeping and standing in their incubator, their bodies pink and mostly hairless. Ju Xiao was impregnated in March with sperm from a panda living at a Guangzhou zoo.

Ju Xiao was under round-the-clock care for the final weeks of her pregnancy, according to the report. The triplets were born within four hours of each other and currently weigh between 230 grams (8 ounces) and 333 grams (12 ounces).

The report said the triplets were only the fourth known to have been born in the world through artificial breeding programs, but it wasn't clear how many had survived from such births.

China has devoted major resources to increasing the numbers of the country's unofficial national mascot and regularly announces the birth of pandas born at zoos and at the Wolong breeding center in the southwestern province of Sichuan, where most wil dpandas are found.

There are about 1,600 giant pandas in the wild, where they are critically endangered due to loss of habitat and low birth rates. More than 300 live in captivity, mostly in China's breeding programs.