A black rhino has been killed by poachers in Kenya's Ol Pejeta Wildlife Conservancy, East Africa's largest black rhino sanctuary.

Ol Pejeta CEO, Richard Vigne, told Xinhua by phone that the seven-year-old rhino was shot dead on Friday night and her horn was hacked off.

"The black rhino was killed by poachers who sneaked into the conservancy on Friday night. Attempts by rangers to pursue them were in vain since it was dark but we have launched investigations into the incident," Vigne said.

He decried an increase in poaching at the conservancy, saying Ol Pejeta had lost five black rhinos in the past six months.

The population of Black rhinos in Africa has been decimated from approximately 100,000 to around 2,500 as a result of poaching in the 1970s and 80s.

Ol-Pejeta has built up its black rhino population from 20 in the 1990s to over 102 today, according to Vigne.

The 90,000-acre Ol Pejeta Conservancy boasts a wide array of wildlife, including the endangered black and white rhinos, elephants, leopards, lions and chimpanzees.

Since late 2009, it has also been home to four of the last seven Northern White Rhinos left in the world.