Zookeepers hoped rare tiger would breed with 'perfect mate'. He killed her.

Melati a female Sumatran Tiger, was killed by a male tiger zookeepers hoped would be her "perfect mate". Phtoo / AP

A potential courtship ended in tragedy Friday at the London Zoo, where staff say a female Sumatran tiger was killed by a male they once hoped would be her "perfect mate".

The zoo detailed the harrowing turn of events in a statement posted to their website Friday. They said the male tiger, Asim, arrived at the zoo 10 days before as part of a breeding programme and was placed in a separate enclosure next to the female, Melati. This granted them time to smell, see and react to one another.

Big-cat introductions could be perilous, even with diligent preparation, the zoo said. On Friday, zookeepers opened the barrier separating their enclosures, optimistic they'd begin the breeding process after showing "obvious" positive signs.

The two animals were wary of each other at first - a normal development, according to the zoo. When they began to interact, however, the cats' caution turned into aggression.

"Zoo staff immediately implemented their prepared response, using loud noises, flares and alarms to try to distract the pair, but Asim had already overpowered Melati," the zoo said. Keepers were able to restrain Asim, but Melati died from the attack.

Asim overpowered Melati, killing her in the attack. Photo / AP

Rob Vernon, a spokesman for the Association of Zoo and Aquariums in the United States, said it was unfortunately impossible to predict the outcomes of these types of encounters.

"Nature also has its own agenda and sometimes introductions don't go as planned - and it sounds like that's what happened in London," he said. "I'm sure the folks in London are just heartbroken. There's so few tigers left - to lose even one, in such a dramatic way - I'm sure they're heartbroken."

On its website, the London Zoo lists the Sumatran tiger the "rarest and smallest subspecies of tiger in the world". Their skins fetch a high price on the black market, making the critically endangered cats a target for illegal hunting, the zoo adds.

Staff were "devastated" and recouping after Friday's drastic turn of events.

The London Zoo welcomed Asim on January 29, writing in a post that the tiger - who was moved to the zoo from Ree Park Safari in Denmark - was a "handsome, confident cat who is known for being very affectionate with the ladies in his life".

Asim and Melati were matched through the European Endangered Species Programme for Sumatran tigers, which sought to rescue the cats from near-extinction, the zoo said.

They seemed to be interested in each other early on, making sounds indicating they had "good intentions."

"We're hoping he'll be the perfect mate for our beautiful Melati," the zoo wrote.