Conservationists in Nepal are to send drone aircraft into the skies in the battle to save the Himalayan nation's endangered tigers and rhinos from poachers.

WWF Nepal said it had successfully tested two unmanned "conservation drones" earlier this month in Chitwan National Park, in Nepal's southern plains, the home of a number of the world's rarest animals.

The remote-controlled aircraft, being used for the first time in Nepal, would monitor the animals and poachers via cameras and GPS to capture images and video, the organisation said in a statement earlier this week.

The aircraft, with a two-metre (6.5-foot) wing span and a range of 25 kilometres (15.5 miles), can stay in the air for 45 minutes, flying at an altitude of up to 200 metres.

"WWF Nepal has been introducing new science and technology to aid ongoing conservation efforts in Nepal. The conservation drones are the latest addition," said Anil Manandhar, the organisation's representative in Kathmandu.

"We believe that this technology will be instrumental in monitoring Nepal's flagship species and curbing illegal wildlife trade."

Thousands of tigers and greater one-horned rhinos, also known as the Indian rhinoceros, once roamed Nepal and northern India but their numbers plunged over the last century due to poaching and human encroachment on their habitat.

Rhinos are killed for their horns, which are prized for their reputed medicinal qualities in China and southeast Asia, while tiger skins, meat and bones are also in high demand.