At least 18 tribal villagers in India's northeast have been arrested for hacking to death a man they suspected of practising witchcraft, police say.

They said they were told to kill the victim by a Hindu goddess who appeared in their dreams.

Mobs have killed at least 200 people over the past five years who they have accused of practising sorcery and witchcraft - mainly in tribal-dominated areas of western and northern Assam state, Indian police say.

The killing took place on Friday at a tea estate village in Assam's Cachar district, 300 kilometres south of the impoverished state's main city of Guwahati.

Cachar district police chief Diganta Bora said by telephone that the attack was "barbaric with a group of hysterical villagers sacrificing the man by piercing his neck with sharp weapons and chanting religious hymns".