At least fourteen alleged members of a gang of rhinoceros poachers have been arrested in Nepal, officials say.
Those arrested include Buddhi Bahadur Praja, the alleged leader of a cross-border smuggling ring.
Police accuse Mr Praja of killing more than 12 rhinos in Nepal in the past six years. There has been no immediate comment from any of those arrested.
Researchers say rhinos are killed so their horns can be used in traditional medicines, despite no proven benefits.
"It was a joint operation by the Nepalese army and the special police," Kamal Jung Kunwar, a senior official at Nepal's Department of National Parks and Wildlife Conservation, told the BBC.
"Fourteen people have been arrested in this operation in the past three weeks. We have seized two guns and four bullets from the gang."
Mr Kunwar said it was the biggest arrest of poachers in a single operation in recent years.
"It was one of our informers who provided us vital clues about the location of these poachers," he added.
Nepal's protected forests were estimated by a census in 2011 to be home to more than 500 rhinos, most of them in Chitwan National Park, about 120km (75 miles) south-west of the capital Kathmandu.
Nepal faced a serious problem of rhino poaching about 10 years ago when the country was affected by civil war between government forces and Maoist rebels.
In 2002, about 37 rhinos were killed by poachers, triggering grave concern over the future of one-horned rhinos.
Their population dropped from an estimated 612 in 2000 to less than 375 in 2005.
But numbers have increased to more than 500 after a series of anti-poaching measures were taken by the authorities.
"This year so far only one rhino has been killed by poachers in Chitwan Park," Mr Kunwar said.
Officials say there are more than 1,000 Nepalese soldiers in the Chitwan national park involved in anti-poaching activities. They operate from more than 40 positions, some deep inside the forest.