One of Kenya's largest game reserves has been forced to halt plans to use drones to monitor its endangered rhinos because of a government ban, park officials said Wednesday.

Ol Pejeta conservancy, home to four of the world's last remaining seven northern white rhinos, said they had planned to launch the 'aerial ranger', equipped with a thermal imaging camera to track wildlife in real time, this month.

But Kenyan authorities have banned the private use of drones, deeming them to be a security threat.

"We have had these plans in the works for over a year now, and we were set for the launch," Elodie Sampere, the conservancy's spokeswoman, told AFP.

"One of the things that has now arisen is that the Kenya government has put a ban in place on private sector drones for the time being."

The Ol Pejeta conservancy, a 90,000-acre non-profit private wildlife sanctuary in central Kenya, has been seeking ways to fend off well-funded and highly-equipped poachers.

On the Asian black market, rhino horn is sought after as an ingredient in traditional medicine and can be more expensive than the equivalent weight in gold.

Last year, 50 rhinos were killed in Kenya by poachers.

The idea to launch a pilotless drone programme in Ol Pejeta was mooted a year ago and some $46,000 was raised via a crowd funding platform.