"We have recorded the death of 16 spotted deer since the past three months. The animals are suspected to have died of rabies. But we have sent the samples to the lab and are waiting for the reports to ascertain the exact cause," Riyaz Khan, Zoo Curator, told PTI.

The official said a vaccination programme is being undertaken at the zoo for the animals as well as the zookeepers.

On being asked whether mongoose bites triggered rabies in the dead animals, Khan said proper care is being taken of zoo inmates and no laxity is entertained.

"Let us wait for the lab reports before speculating," he said.

The zoo houses around 120 spotted deer.

The Central Zoo Authority (CZA) has asked for a detailed report from the National Zoological Park in this regard.

CZA runs its breeding programmes for the Royal Bengal Tiger, Indian rhinoceros, swamp deer, Asiatic lion, brow-antlered deer and red jungle fowl, at the Delhi zoo.