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.

The Uttar Pradesh government has ordered a judicial probe into the deaths of at least 30 people in stampedes at India’s Kumbh Mela festival, where millions of Hindu devotees gathered for a ritual bath at the confluence of three sacred rivers.

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.