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.

The late release of casualty figures at the gathering of millions of people was seen as shielding the political fortunes of a local leader with national aspirations.