By Baldev Chauhan BBC correspondent in Himachal Pradesh

It is not clear how many eunuchs are actually castrated

The 21-year old man, Sonu, has been working as a drummer with a group of eunuchs in the northern state of Himachal Pradesh for the last two years.

He told the police that earlier this week he travelled with two of the eunuchs to the city of Ludhiana in the neighbouring state of Punjab.

"I was given tranquilisers in my food and once I fell unconscious the crude surgery was carried out to remove my penis," Sonu, a member of India's lowest caste, the Dalits, told the police.

"As if this wasn't enough, I was then transported to Agra [in the state of Uttar Pradesh] where I regained my senses."

It is not clear why the eunuchs would have wanted to cut off the man's penis.

Eunuchs in India generally live in self-contained communities, ostracised by the rest of society.

They usually earn their living by turning up uninvited at weddings, births and other major family events and singing until they are paid enough to go away.