In this photograph taken, on July 31, 2006, forest workers look at a dead rhinoceros at the Chitwan National Park in southern Nepal

Tikaram Paudel, an official at the Chitwan National Park which is home to most of the country's rhinos, said police arrested Buddhi Bahadur Praja, the alleged kingpin of a network extending from Nepal to China's Tibet, in mid-September.

His arrest in the popular tourist city of Pokhara helped authorities uncover a network of poachers, said Paudel.

"He would supply the rhino horns to Kathmandu-based smugglers who would supply them to Tibetans," he said.

Police have accused the 55-year-old smuggler of killing 12 rhinos over the past six years.

Police arrested four more smugglers and eight poachers in an operation that followed Praja's capture, recovering two guns and four bullets from the poachers living in villages near the country's national parks.

A 14th man was arrested for supplying weapons.

Rhino poaching in Nepal carries a maximum penalty of 15 years in jail and a 100,000-rupee ($1,013) fine.

Thousands of rhinos once roamed the plains of Nepal, but their numbers have plunged over the past century due to poaching and human encroachment of their habitat.

Around 534 rhinos roam Nepal's protected areas including the Chitwan National Park, according to a census in 2011.

The animals are killed for their horns, which are prized for their supposed medicinal qualities in China and Southeast Asia.

A single horn can sell for tens of thousands of dollars on the international black market, and impoverished Nepal's porous borders, weak law enforcement and proximity to China have made it a hub for the illegal trade.