Police arrested Indian "cockroach" movement founder Abhijeet Dipke, according to several media reports on Saturday, after he was detained on Friday ahead of a Delhi rally that drew hundreds of people waving the national flag and demanding the resignation of India's election chief.
Dipke was arrested to prevent a breach of the peace and will be called before a Special Executive Magistrate on Saturday, broadcasters NDTV and India Today said.
Delhi police did not immediately respond to an emailed request for comment.
The youth-led Cockroach Janta Party (CJP), opposition groups and student organisations have held near-daily protests this month demanding Chief Election Commissioner Gyanesh Kumar's resignation over a revision of voter lists that they say favours Prime Minister Narendra Modi's Bharatiya Janata Party (BJP).
More than 130 million voters were deleted during the revision. The Election Commission has denied favouring any party and said wrongly deleted voters can re-enrol. The BJP has accused rivals of trying to undermine democracy by wrongly questioning legitimate electoral processes.
Student activist Neha Bora, a prominent face of the protests, who was also detained on Friday as she tried to reach central Delhi with dozens of supporters, was released on Saturday.
"Please, spare the people of India. Impeach Gyanesh Kumar and halt SIR (special intensive revision), so that the ordinary citizens of this country can breathe a sigh of relief, feel at ease, and have their voting rights ensured," Bora told ANI news agency after she was released.
Dipke was detained on Friday as he stepped out of a house in central Delhi, with police hauling him into a police car and driving away after a brief argument.
Dipke had called Friday's protest in support of two CJP leaders detained and sent to jail this week for five days for demonstrating at a protest site in violation of a ban.
Earlier on Friday, police had met Dipke and warned him against going ahead with the protest.
The cockroach movement has emerged as one of the biggest political challenges faced by Modi and the BJP in the prime minister's 12 years in power.
A weeks-long sit-in by supporters of the movement earlier this year forced Education Minister Dharmendra Pradhan's resignation over exam paper leaks.