A senior police officer said at least 30 people died as a crowd panicked at the Hindu Kumbh Mela mega-festival in the northern city of Prayagraj.

Moments before a deadly stampede at the world's biggest religious gathering in India, Hindu devotees queuing to take a spiritual bath in a river said they pleaded with police to open barricaded routes to thin out a surging crowd.

Hindu devotees, mystics and holy men and women have gathered in India's northern city of Prayagraj for the Maha Kumbh festival, the world's largest religious gathering.

The Hindu festival that turned deadly in northern India on Wednesday is a religious gathering with deep spiritual meaning for devotees who come by the millions to take a cleansing dip in waters they consider sacred.

Millions of devout Hindus thronged the northern Indian city of Prayagraj on Thursday for the Maha Kumbh festival, a day after dozens died in a stampede on the most auspicious day of the six-week event.

Millions of Hindus are gathering in a northern Indian city for the Maha Kumbh festival, the world’s largest religious congregation.