Lion tears out lioness's throat in front of horrified Belgian zoo staff as the animals are introduced for breeding program

During their first introduction for a zoo breeding program on Thursday, a lion tore out a lioness's throat in front of horrified staff as they were forced to watch on.

Male big cat Nestor and female Maya had been getting used to each other's scent from behind bars in the Belgian Bellewaerde Park.

Nestor, also known as 'Lion King', had recently moved from Antwerp Zoo to Ypres in West Flanders as part of a breeding program for endangered species.

The 12-year-old predator was initially meant to mate with two Czech lionesses, sisters Maya (two) and Numa (one).

The three wild animals were given the opportunity to adapt to each other's presence from behind a barrier for a few days, and zookeepers reportedly saw no signs of aggression between the lions.

Nestor, also known as 'Lion King', tore out the throat of his intended mating partner Maya at Bellewaerde Park's zoo in Belgium on Thursday

Maya and Nestor were part of a breeding program for endangered species 

Staff then decided on Thursday it was time to let Nestor and Maya outside together with no bars between the two.

According to the zoo, things were going smoothly when the two cats first came face-to-face with one another.

But this quickly changed as the lions began showing signs of aggression.

'They started fighting and Nestor bit Maya in the throat,' spokesperson Filip Van Dorpe told local media.

The zookeepers attempted to save the wounded lioness, but it was too late.

'A distress signal that Nestor knows to return to his accommodation could no longer help,' he added.

Van Dorpe expressed his disappointment on the incident, calling it 'very unfortunate'.

'They remain wild animals, this of course also happens in nature. 

'We deeply regret this, everyone in Bellewaerde is devastated. We went from pride to sadness in one day'.

Having only said goodbye to Nestor a couple of weeks ago, the zookeepers at Antwerp Zoo still have fond memories of the lion, reported VRT News.

The zoo's spokeswoman Ilse Segers said that the news that Nestor has killed his intended mating partner has been met with sorrow and shock. 

'We all have reacted with complete disbelief'. 

Nestor was born in Antwerp Zoo, and according to staff there, he had never shown any signs of aggression.

Segers told VRT News: 'When he was born he was little on the shy side, but since then, he has really opened up. 

'He was always gentle with his cubs and with his former partner Tasa. You did have to leave him alone while he was eating though. He didn't want anyone near him then'.

Local media has reported that there will now be a waiting period before Nestor is introduced to other lionesses.

He will also remain in the enclosure and the breeding program is expected to continue.