Superstition of his parents that a dip in the Ganga could cure him of cancer cost a seven-year-old child his life in Haridwar on Wednesday, police said.

The boy's parents kept chanting mantras on the banks of Har-ki Pairi while his aunt allegedly dipped him repeatedly in the Ganga ignoring his loud cries, until he suffocated and died, they added.

Bystanders tried to stop the woman but she refused to listen to them, the police said.

Eyewitnesses reported the incident to the police, Station House Officer of the Har-ki-Pairi police station Bhavna Kainthola said.

The child's parents and aunt have been held for interrogation, the SHO said.

The boy was suffering from blood cancer and resided with his parents in Delhi, she said.

He died of drowning, the SHO said, adding that further inquiry in the case is underway.