VIENNA (REUTERS) - Giant panda Yang Yang gave birth nine days ago and CCTV monitoring at Vienna's Schoenbrunn Zoo did not show her secret until late last week - she had not one but two cubs keeping warm between her massive paws.

Pictures and video footage from the zoo showed the two tiny pink cubs resting on Yang Yang's chest as she lay on her back.

"It sounded as though two cubs were squealing, but we only ever saw one," zoo director Dagmar Schratter said in a statement on Tuesday (Aug 16).

"On Friday, the zookeepers were first able to make out two of them on the screen."

Yang Yang is being monitored by cameras in a private pen so as not to disturb her and panda cubs are rarely seen because their mothers constantly warm them between their paws.

Yang Yang has given birth to three other cubs, all of which are now in China.