A painted image of the Hindu goddess Kali is propped up against a stone in the dirt, her long red tongue goading terrified worshippers into submission. From one of her eight flailing arms a severed head dangles, her neck is adorned by a necklace of bleached human skulls.

There are bloodstains on the cracked wall behind the terrible postcard-size image and, around the dark room, splattered gore on the heavy wooden furniture. These dark marks bear witness to a child sacrificed in the name of the abominable goddess.

Through the doorway, in the distance, colourfully dressed women are bent double, toiling in the fields, their faces worn and wrinkled from the sun, their hands cracked from digging at the dry earth from dawn until dusk.

It's an intolerable life in the remote village of Barha, a squalid collection of mud-bricked farmers' dwellings in the heart of the impoverished province of Khurja, Uttar Pradesh. This corner of rural India is a lawless place of superstitions and deep prejudice. The region, known for its sugarcane, is a tortuous eight-hour drive from Delhi and a lifetime away from the 21st century.

In Bulandshahr, the nearest town of any description, locals whispered darkly of happenings in Barha. Their advice was unanimous: 'Don't go. It is an evil place. The people there are cursed.'

Sumitra Bushan, 43, who lived in Barha for most of her life, certainly thought she was cursed. Her husband had long abandoned her, leaving her with debts and a life of servitude in the sugarcane fields. Her sons, Satbir, 27, and Sanjay, 23, were regarded as layabouts. Life was bad but then the nightmares and terrifying visions of Kali allegedly began, not just for Sumitra but her entire family.

She consulted a tantrik, a travelling 'holy man' who came to the village occasionally, dispensing advice and putrid medicines from the rusty amulets around his neck.

His guidance to Sumitra was to slaughter a chicken at the entrance to her home and offer the blood and remains to the goddess. She did so but the nightmares continued and she began waking up screaming in the heat of the night and returned to the priest. 'For the sake of your family,' he told her, 'you must sacrifice another, a boy from your village.'

Ten days ago Sumitra and her two sons crept to their neighbour's home and abducted three-year-old Aakash Singh as he slept. They dragged him into their home and the eldest son performed a puja ceremony, reciting a mantra and waving incense. Sumitra smeared sandalwood paste and globules of ghee over the terrified child's body. The two men then used a knife to slice off the child's nose, ears and hands before laying him, bleeding, in front of Kali's image.

In the morning Sumitra told villagers she had found Aakash's body outside her house. But they attacked and beat her sons who allegedly confessed. 'I killed the boy so my mother could be safe,' Sanjay screamed. All three are now in prison, having escaped lynch mob justice. The tantrik has yet to be found.

Police in Khurja say dozens of sacrifices have been made over the past six months. Last month, in a village near Barha, a woman hacked her neighbour's three-year-old to death after a tantrik promised unlimited riches. In another case, a couple desperate for a son had a six-year-old kidnapped and then, as the tantrik chanted mantras, mutilated the child. The woman completed the ritual by washing in the child's blood.

'It's because of blind superstitions and rampant illiteracy that this woman sacrificed this boy,' said Khurja police officer AK Singh. 'It's happened before and will happen again but there is little we can do to stop it. In most situations it's an open and shut case. It isn't difficult to elicit confessions - normally the villagers or the families of the victims do that for us. This has been going on for centuries; these people are living in the dark ages.'

According to an unofficial tally by the local newspaper, there have been 28 human sacrifices in western Uttar Pradesh in the last four months. Four tantrik priests have been jailed and scores of others forced to flee.

The killings have focused attention on Tantrism, an amalgam of mystical practices that grew out of Hinduism. Tantrism also has adherents among Buddhists and Muslims and, increasingly, in the West, where it is associated with yoga or sexual techniques. It has millions of followers across India, where it originated between the fifth and ninth centuries. Tantrik priests are consulted on everything from marital to bowel problems.

Many blame the turn to the occult on the increasing economic gap between rural and urban India, in particular the spiralling debts of cotton and tobacco farmers, linked with high costs of hybrid seed and pesticides, that has led to record numbers of farmers committing suicide.

According to Sanal Edamaruku, president of the Indian Rationalist Association, human sacrifice affects most of northern India. 'Modern India is home to hundreds of millions who can't read or write, but who often seek refuge from life's realities through astrology or the magical arts of shamans. Unfortunately these people focus their horrific attention on society's weaker members, mainly women and children who are easier to handle and kidnap.'

Tantriks caught up in the crackdown in Uttar Pradesh say their reputation is being destroyed by an insane minority. 'Human sacrifices have been made in this region since time immemorial,' says Prashant, a tantrik who runs a small 'practice' from his concrete shell of a home on the outskirts of Bulandshahr. 'People come to me with all sorts of ailments. I recommend simply pujas and very rarely animal sacrifices.'

In her squalid home Ritu Singh rocks back and forth, beating her chest in grief. She has been mourning since the day her son Aakash's body was discovered in a sewer outside Sumitra Bushan's home. Her husband, Rajbir, said: 'We expect them to be jailed or fined but they won't spend longer than a few years in prison for what they have done. They were my neighbours, they ate in our house. The Tantrik who made them do this has disappeared, they will never find him.'