Zoo spokesman Tobias Stenbaek Bro said Monday that he and the zoo's scientific director, Bengt Holst, received several threats over the telephone and in emails. They quoted one email as saying: "The children of the staff of Copenhagen Zoo should all be killed or should get cancer."

The giraffe, Marius, was killed on Sunday using a bolt pistol, then skinned and fed to lions in front of visitors, including children.

The killing triggered a wave of online protests and debate about zoo conditions.

The zoo said it killed Marius to prevent inbreeding, and it defended the public feeding as a display of scientific knowledge about animals.