A Sumatran tigress has been killed by a potential mate in London Zoo.

It happened as Zookeepers tried to introduce the pair for the first time.

The male tiger, seven-year-old Asim, had arrived in London ten days earlier as part of a Europe-wide conservation breeding programme and it was hoped they would be able to breed into the future.

Asim was kept separate from nine-year-old tigress Melati since his arrival, however the pair were able to “see, smell and react to each other” in their adjoining enclosures.

Sumatran tigers Jae Jae and Melati are seen during a photocall at ZSL London Zoo in London, Britain, 03-01-2019. Image:  Tim Ireland/Xinhua News Agency/PA Images

In a statement this evening, London Zoo said, “following careful monitoring,” experts today decided that the time was right to introduce them.

“As with all big cats, introductions, however carefully planned, are always considered to be high risk,” it said.

“This morning, the two tigers were in separate paddocks and the adjoining door was opened to allow them to meet. Asim approached Melati and, as expected by keepers, the two tigers were initially cautious.

“Their introduction began as predicted, but quickly escalated into a more aggressive interaction. 

“Zoo staff immediately implemented their prepared response, using loud noises, flares and alarms to try and distract the pair, but Asim had already overpowered Melati.”

Zookeepers were eventually able to secure Asim in a separate paddock – however, the zoo’s vets confirmed that Melati had already died.

The zoo said staff are “devastated by the loss of Melati and we are heartbroken by this turn of events.”

The Tiger Territory will remain closed for the rest of the day.