The number of rhinoceros killed in Zimbabwe parks decreased to 23 this year from 30 in 2010 as parks authorities stepped up high-tech efforts to track poachers, state media reported Monday.

"We have just above 700 black and white rhinos and 23 have been poached this year," Caroline Washaya, Zimbabwe Parks and Wildlife Management Authority public relations manager told The Herald newspaper.

"We managed to arrest 37 poachers and illegal dealers in rhino horns to date," she added.

Zimbabwe and its southern neighbour South Africa have been hard hit by rhinoceros poachers motivated by the lucrative market for the horn in Asia where it is used for medicinal purposes.

Washaya said parks authorities had been using methods such as placing tracking chips in the rhinos' horns, or removing the horns altogether, to prevent poaching.

"This year, a total of 100 rhinos were immobilised for ear notching and horn implanting to facilitate individual identification and monitoring in the field," she said.

Last month a US-based animal protection group, the International Rhino Foundation, launched Operation Stop Poaching Now to raise funds to equip rangers in Zimbabwe and South Africa with kits to better track rhino poachers.

The so-called "crime-scene kits" contain a camera, a metal detector, a GPS system, finger-printing materials and sealable evidence bags, according to the Foundation.