Dozens of rare one-horned rhinos have gone missing in south-western Nepal in recent years, say conservationists.

A recent census carried out at a national park in Bardiya suggested there were only 26 rhinos left. The number stood at 83 four years ago.

Rhinos have also dwindled in Chitwan park where the population has fallen to 405 from more than 500 in 2000.

Poachers are suspected to have killed the animal whose horn is sought after for its alleged aphrodisiac qualities.

Some reports have suggested that some rhinos may have moved across the borders to India, but a senior conservation official, Phanindra Kharel, has ruled that out.