A coven of witches chopped off a man's arms and burned him alive when he asked them for help treating his sick 10-year-old son, police say.

Brijlal Chopra's wife and son told police they watched helplessly as he was stabbed repeatedly and hacked with axes before the witches set him on fire with kerosene-soaked rags.

'They were laughing and dancing around his body to music while he screamed in agony. In the end there was just a pile of ashes left,' said a police spokesman in Mandla, Madhya Pradesh, the closest city to where the ritual slaying happened.

Black magic: The coven of witches, including Parvati, centre, and six of her followers, who have been arrested after allegedly hacking off a man's hands and burning him alive in front of his wife and 10-year-old son

Mr Chopra had sought out the local witchdoctor - known only as Parvati - for treatment for his 10-year-old son, said police.

But as soon as the family reached her commune, Parvati branded Mr Chopra a rival sorcerer and ordered her disciples to kill him.

His wife Sushma later told police: 'It was sickening. They surrounded him and took turns to stab him with tridents and hack at him with an axe.

'They cut off his hands because they said that was where his power was.

'My husband told them he had no powers, no witchcraft, but they wouldn't listen. The more he screamed, the more they sang and the more they laughed.

'Then to make sure his power was gone for ever, they said they had to burn him. This was in front of our son who was terrified.'

Parvati and her followers allowed Sushma and her son to leave, but vowed to curse them if they told anyone. The pair ignored the threats and travelled all night to the nearest police station where they reported the killing.

Grief: Sushma Chopra is comforted by her son after the incident. The witches were said to have threatened them with a curse if they reported the killing, but they ignored the threat and travelled all night to find police

Police say the witch and six of her followers are in custody awaiting trial for murder.

'We confiscated literature on witchcraft, as well as axes and tridents from the scene. We have also recovered some ashes for forensic tests,' said a police spokesman.

The killing comes amid growing hysteria over witchcraft in India. Earlier this month a 35-year-old woman in Bihar was dragged from her home, beaten, and forced to eat faeces after she was blamed for casting a spell which caused the death of a neighbour.

Just a week before that, 10 people were arrested in Odisha over the torture of a 60-year-old woman who was left in a critical condition after she was blamed for the death of an 18-year-old boy. Medical records showed he in fact died of malaria.

A UN official last year said that archaic cultural practices such as lynching women branded as witches persisted in India partly because they were social sanctioned and not treated as as crimes by police.