LONDON -- Up to 35,000 elephants were killed last year for their tusks, the head of a charity told NBC News.

Charlie Mayhew, the chief executive of Tusk Trust, said: "What we have witnessed over the last 18 months or two years has been a significant escalation in the poaching of both rhino for rhino horn and elephant for ivory, fueled by sort of a dramatic increase in demand from consumers in the Far East.

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"Last year we believe that as many as 35,000 elephants may have been slaughtered for their ivory," he added. "South Africa lost 434 rhino last year. This year we know that they've lost more than 170 rhino. That's more than an average of one every 15 hours and that is just South Africa alone."

A rhino horn is worth as much as $40,000 on the black market.

Britain's Prince William and Princess Katherine have thrown their star power behind the organization.

Speaking at the London premiere of documentary "African Cats," which was held in aid of Tusk Trust, the price said: "We must act now, coherently and together if the situation is to be reversed and our legacy -- our global, natural legacy -- preserved. Tomorrow will be too late."

For more on the plight of Africa's wild animals and the efforts to save them, click on the video above.

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