India, June 20 -- As the sun began to set over Delhi's Jantar Mantar on Saturday evening, police announcements crackled through loudspeakers, informing protesters that the gathering had been declared illegal and that they should disperse.

The Cockroach Janta Party (CJP) leaders, and some protesters showed little sign of backing down.

Protesters continued banging steel plates and spoons, while CJP founder Abhijeet Dipke posted a video urging supporters across the country to launch peaceful "Jail Bharo" protests if he was arrested.

The demonstration, centred on demands for Union education minister Dharmendra Pradhan's resignation over examination-related controversies, drew students and supporters from several states, with protesters ban...