Two female Asiatic lion cubs were born in Rome on 29 April, a first in the Bioparco zoo's history.

The zookeepers only suspected that the cub's mother was pregnant two days before she gave birth. 

They then discovered that the cubs had survived their birth after the zookeepers heard small yelps coming from the lions' enclosure.

"A lion cub is still a lion even when it's small," said Klaus Friedrich, a veterinary doctor at the zoo.

"Today the two cubs weigh six kilos. When they needed a health check and a vaccine, they became lionesses. Only six kilos, but they took out their claws and went 'Grrrr'."

The Asiatic lions were listed as critically endangered in 2000. But since then, the population size has been steadily increasing. In 2015, there were an estimated 523 lions in the world. This year, that number has jumped to almost 700 in India alone. 

The Rome zoo is currently closed, so visitors will have to wait to see these rare cubs in person. 

Video editing: Sam Cordell