Wildlife experts warn that a rare northern white rhino is closer than ever to extinction following the death of one of only six of animals left.

Suni – as he was known – was one of the last two males in a breeding programme at a wildlife sanctuary in Kenya.

Conservationists have struggled to reverse a decline in several African rhino species due to ivory poaching in recent decades.

Rhino horn sold on the streets of major Asian cities was last year more valuable than gold or platinum, with traders asking for about $65,000 per kg of rhino horn.