London Zoo has a party animal problem and it’s not the penguins or tigers, who have reportedly been victims of drunken party goers at the zoo’s late-night events.

The popular after-hours parties at the zoo are being investigated by Westminster Council over claims of guests throwing glasses at animals, pouring beer on tigers and trying to climb into the penguin enclosure, among other offences.

More than 64,000 people have signed a petition to stop the popular ‘Zoo Lates’ events, which touts “flamboyant stilt-walkers, hilarious comedy, fantastic food from around the world, and the chance to see incredible wildlife after hours”.

The over 18s event does sell alcohol, which has seemingly been at the root of the problem, with zookeepers reporting a slew of drunken behaviour including guests crushing butterflies, touching penguins and pouring drinks on people and animals, notably at the tiger enclosure.

London Zoo said the wellbeing of its animals was always its priority, but has continued to hold the events, citing “additional security” as a measure to prevent future incidents.

People for the Ethical Treatment of Animals (PETA) has spoken out against the event, with PETA spokesperson Ben Williamson telling AM2: “Patrons of what London Zoo actively promotes as "a wild night out" are there to party. Rowdy, drunk humans and captive wild animals make for an even more dangerous combination for all concerned.

“It's bad enough that the London Zoo's permanent residents have no way of escaping their day-to-day confinement, but to deliberately encourage and promote events which pose a threat to them defies belief.”

London Zoo defended its actions, stating that animal wellbeing was at the top of the institution’s agenda.

"We would like to reassure those people that have taken the time to sign the petition, that we would not continue to run any event or activity which compromised this, in any way,” said a London Zoo spokesperson.

"We are taking every measure to ensure our 'Zoo Lates' evenings are positive experiences for both our animals and visitors and will continue to work closely with Westminster Council to make sure they are satisfied we are meeting and exceeding all license requirements."