The carcasses of nearly 90 elephants have been discovered near a wildlife sanctuary in Botswana, conservationists say.

Elephants Without Borders reports it found a total of 87 dead elephants in recent weeks during an aerial survey of the elephant population.

It says the slaughter is the largest scale of poaching deaths seen in Africa, coinciding with Botswana’s anti-poaching unit being disarmed. All 87 had their tusks removed.

Five white rhinos had been also poached in the past three months.

“I’m shocked, I’m completely astounded. The scale of elephant poaching is by far the largest I’ve seen or read about anywhere in Africa to date,” Elephants Without Borders founder Dr Mike Chase told BBC.

“When I compare this to figures and data from the Great Elephant Census, which I conducted in 2015, we are recording double the number of fresh poached elephants than anywhere else in Africa.”

The survey estimated a third of the continent’s elephants had been killed in the past decade, while 60 per cent of Tanzania’s elephants have been slaughtered in the past five years.

Botswana previously had a unforgiving reputation for dealing with poachers and had largely protected the animals unseen in other areas.

Some 130,000 elephants were known to retreat from Angola, Namibia and Zambia and stay within the boundaries of Botswana, where armed anti-poaching units were established.

Mr Chase blamed the disarmament of the country’s anti-poaching unit for the latest killings found deep in Botswana – close to protected wildlife sanctuary Okavango Delta.

“People did warn us of an impending poaching problem and we thought we were prepared for it,” he said.

“The poachers are now turning their guns to Botswana. We have the world’s largest elephant population and it’s open season for poachers.

“Clearly we need to be doing more to stop the scale of what we are recording on our survey.”

He said while the Botswana 2018 Wildlife Aerial Survey is only half done, he expects the final figure of poached elephants will increase significantly.

“This requires urgent and immediate action by the Botswana government,” Mr Chase said.

“Botswana has always been at the forefront of conservation and it will require political will.

“Our new president must uphold Botswana’s legacy and tackle this problem quickly. Tourism is vitally important for our economy, jobs, as well as our international reputation, which is at stake here as being a safe stronghold for elephants.”