Media playback is unsupported on your device Media caption Prince William said the illegal trade in rhino horn was "ignorant, selfish and utterly wrong"

The Duke of Cambridge is calling for action to stop the illegal trade in rhino horns, warning that the animals are being slaughtered at such a rate they could soon be extinct.

"Along with elephants, they're two of the most heavily poached animals currently in the world," Prince William told the BBC.

"If we don't do something about them, it's going to be a tragic loss for everyone."

The royal patron of wildlife charity the Tusk Trust has just lent his support to a programme - run by conservation charity the Aspinall Foundation - to return three rare black rhino born in captivity and raised in Kent to the wild in Tanzania.

Poachers are killing more rhino in Africa than ever before, conservationists warn, with horns fetching up to $60,000 (£38,000) a kilo on the black market.

'Neglect and ignorance'

The practice is undermining efforts to stabilise the populations of both black and white rhino which together total some 18,000 in Africa, according to the conservation charity WWF.

Image caption Conservationists say animals must have a chance to return to the wild

It estimates that despite being "critically endangered", rhino have been shot in their hundreds this year.

Demand is being driven by a market in Asia which believes powdered rhino horn can cure ailments including cancers - despite no scientific evidence to back this up.

Prince William said: "There's a massive need for education on poaching... rhinos are very vulnerable animals and I think a lot of people don't realise what happens and how rhino horn, or ivory, ends up in a particular area.

"I think [we need to] make people aware of how delicate and fragile these animals are, and how much damage we are doing to them and to the wildlife and natural ecosystem around them just by our neglect and ignorance."

He said those who knowingly took part in the illegal trade were "extremely ignorant, selfish and utterly wrong".

Speaking at Port Lympne wildlife park in Kent - where the three young rhino were raised - the duke said he was keen to work with communities on the ground to ensure they benefited as well as the animals.

'Culture shock'

"Otherwise many of these countries in Africa will lose prime tourism, prime assets," he added.

The three black rhino, which have now arrived at their new home in Mkomazi National Park in northern Tanzania, have armed guards with them 24 hours a day.

Black market in rhino horn Some people in south east Asian countries like Vietnam and China believe it has potent medical properties

When ground into powder, believed to cure headaches, fever, heart disease and some cancers

Use dates back to about 300BC

Essentially made of keratin - the same protein that forms our own nails and hair

No scientific evidence to suggest it has any medicinal qualities

Damian Aspinall, from the Aspinall Foundation, said they would have to cope with the stress of adjusting from a "cosy life" in England to the wilds of Africa.

"We think it's fantastic sending them home, but they probably think 'what the hell, strange noises, strange climate'. I think any animal you send back will have a bit of a culture shock."

He said educating people in China that there was no medical value in rhino horn would be hard as they had been brought up their entire lives to believe it.

But he said he believed technology could help in the fight - potentially fitting transmitters to horns, or using unmanned drone aircraft to monitor the movement of both rhino and poachers.

As he fed Zawadi, a five-year-old female now in Tanzania, Prince William explained that his love of rhino stemmed from his time helping to hand rear them at a friend's reserve in Kenya.

He explained that despite looking "bombproof", they were sensitive creatures with wonderful characters.

But his tone changed as he explained how Max, one of those he fed, was killed just this year by poachers in an act he described as a "complete waste".

'Someone's mantelpiece'

"Sadly, he ran into the wrong people and he is now on someone's mantelpiece somewhere probably," he said.

The duke said he wanted to send a message of support to all those taking part in the fight to stop the killing of rhino, but he also wanted to see more education and awareness raised about the issue.

Tusk Trust chief executive Charlie Mayhew said the killing of both white and black rhino was out of control.

Image caption The three black rhino are settling into their new home at Mkomazi National Park in northern Tanzania

He said 13 black rhino were killed in South Africa in 2007, compared with 434 just four years later.

Recent rumours that rhino horn powder cured a prominent (but unnamed) politician's cancer have seen prices rise higher than those for gold.

The Aspinall project had been a collaborative effort, with charities and big business coming together - a message echoed by the duke.

"These guys are prehistoric looking. They are the most incredible things and do we really want to live in a world 20, 30 years down the line where there's no such thing as a 'big five' [elephants, lions, rhino, cape buffalo and leopard]?" he said.

"It'll be the big four, then possibly the big three and then where do we go after that?

"Are our grandchildren ever going to be able to see the big five? I think that's terribly sad and that should never happen."