Police have become involved after a video showing a man slapping a hippopotamus on the behind at a Los Angeles zoo, where officials have posted new signs warning visitors against interaction with the animals held in captivity.

The Los Angeles Police Department became involved after a video showing a man climbing over a barrier and then slapping the hippo’s rear end went viral. In the video, the man slowly approaches the two hippos after climbing a barrier, loudly slaps one of the hippos, then retreats with his hands in the air in a gesture of victory.

“Any unauthorised interaction with an animal is unsafe for the animal and potentially unsafe for the patron,” April Spurlock, a zoo spokesperson, told the Los Angeles Times. “It is never appropriate for anyone to attempt to have contact or interaction with any animal outside of our staff-led animal experiences”.

While the new signs warning visitors from entering exhibits is the first of their kind, state law in California prohibits the public from entering zoo enclosures, and the offence can carry with it a misdemeanour charge. That information is made available to visitors of the LA Zoo elsewhere, like on maps and at access points to the zoo from the outside.

It is not clear whether the hippos came away with any damage or lasting stress from the incident, but the animal did not have any obvious signs of injury. The case is not being investigated as one of animal cruelty, and is instead being considered as a case of trespassing.

Animals take shelter from Hurricane Irma at Zoo Miami Show all 8 1 /8 Animals take shelter from Hurricane Irma at Zoo Miami Animals take shelter from Hurricane Irma at Zoo Miami Jennifer Nelson, senior keeper at Zoo Miami, leads a cheetah named Koda to a hurricane resistant structure within the zoo, Saturday, Sept. 9, 2017 in Miami. AP Photo/Wilfredo Lee Animals take shelter from Hurricane Irma at Zoo Miami Ryan Martinez, a trainer at Zoo Miami, places an Eurasion Eagle Owl into a crate AP Photo/Wilfredo Lee Animals take shelter from Hurricane Irma at Zoo Miami Flamingos at Zoo Miami, are shown in a temporary enclosure in a hurricane resistant structure within the zoo, (AP Photo/Wilfredo Lee) Animals take shelter from Hurricane Irma at Zoo Miami Brown pelicans and an American white pelican take refuge in a shelter ahead of the downfall of Hurricane Irma at the zoo in Miami REUTERS/Adrees Latif Animals take shelter from Hurricane Irma at Zoo Miami An African crested porcupine is moved into a shelter ahead of the downfall of Hurricane Irma at the zoo in Miami, Florida, REUTERS/Adrees Latif Animals take shelter from Hurricane Irma at Zoo Miami A macaw parrot looks out of it's cage after being put into a shelter REUTERS/Adrees Latif Animals take shelter from Hurricane Irma at Zoo Miami An African grey parrot is moved into a shelter ahead of the downfall of Hurricane Irma REUTERS/Adrees Latif Animals take shelter from Hurricane Irma at Zoo Miami Cheetahs are photographed in a shelter ahead of the downfall of Hurricane Irma at the zoo in Miami, Florida, REUTERS/Adrees Latif

Ms Spurlock said that these sorts of incidents are rare, and it does not appear as though the video is representative of any larger trend towards harassing the animals.

“We seriously feel this was an isolated incident,” she told the Los Angeles paper. “Most people know not to go in with the animals. It’s common sense”.