Another giant panda cub has been born at Vienna's Schoenbrunn Zoo - the fourth time that mother Yang Yang has conceived naturally.

Such an event is very rare - most panda breeding centres resort to artificial insemination.

The cub's sex is not known yet. The tiny pink creature - born at 05:05 local time (03:05 GMT) - is just 10cm (four inches) long and weighs 100g (3.5 ounces).

Yang Yang's other cubs are now in China, where an estimated 1,864 live in the wild.

The zoo's panda area has been closed to let Yang Yang rear her cub in peace and the father, Long Hui, is being kept away for the cub's safety.

Zoo director Dagmar Schratter said Yang Yang "is taking good care of her offspring, but one must bear in mind that the mortality rate of giant pandas in their first year is nearly 40%".