Four lions at Barcelona Zoo have tested positive for COVID-19, veterinary authorities said on Tuesday, in one of just a handful of documented cases globally in which large felines have contracted coronavirus.

Three females named Zala, Nima and Run Run and Kiumbe, a male, were tested after keepers noticed they showed slight symptoms of COVID-19.

Two staff at the zoo also tested positive for COVID-19, the authorities said, after the crisis was first detected in November.

Keepers carried out PCR tests on the lions in the same way as humans are tested as the animals are familiar to contact with the zoo staff. The four-year-old male and the females, who are all 16, have had no contact with other animals at the zoo.

"The lions were given veterinary care for their mild clinical condition - similar to a very mild flu condition - through anti-inflammatory treatment and close monitoring, and the animals responded well," the authority in Barcelona was quoted as saying by Reuters. Authorities are examining how the lions became infected.