The panda cub born here eight days ago was found dead in the cage of its 270-pound mother this morning, apparently crushed under her weight.

It was the first cub of the rare giant pandas to be born outside China, despite determined efforts at zoos in Washington, Tokyo and London.

Chapultepec Zoo's technical director, Jean Schoch, said the apparent suffocation occurred overnight and was discovered when an attendant found the mother licking the cub this morning in a seeming attempt to revive it.

Schloch said the mother, Ying-Ying, had been exemplary during the first week. "You could tell she liked him," said Schoch. "She never put him on the floor except to eat and drink." The sex of the cub, named Xinli, will only be determined in an upcoming autopsy. Xinli had doubled its birth weight of 3 1/2 ounces.

The father, Pe-Pe, was kept separate following the birth but was back in the cage today with Ying-Ying. Schoch said he had hopes for another pregnancy by a now more experienced mother.

Noting the artificial insemination of the panda at the National Zoo in Washington this spring, Schoch said, "I will call up Dr. [Theodore] Reed and tell him about the movements of the pandas and what we have learned."

Mexico City, at 7,000 feet altitude, is closer to the height of wild pandas' habitat, about 10,000 feet. This had led to one theory that the reluctance of pandas to mate in the capitals of other countries receiving them from China is related to the low altitude.