A giant panda cub at a Tokyo zoo appears to be in good health, crying loudly while being gently held by its mother, the zoo said Tuesday, one day after the cub was born.

"(The cub) cries vigorously and we saw it suckling the mother panda's breasts four or five times last night," an official at Ueno Zoological Gardens said.

Its mother, Shin Shin, has been holding her cub to keep it warm, even though she appears tired from lack of sleep and going without food or water, said the zoo's director Yutaka Fukuda. The zoo has not yet been able to confirm whether the cub is drinking its mother's milk, he said.