Four people were arrested in Mathura on Monday while they were on their way to Hathras from Delhi, police said.
The police claimed they were associated with the Popular Front of India (PFI) and an allied outfit. Uttar Pradesh police had earlier sought a ban on the PFI.
The four, who were in a car, identified themselves as Atiq-ur Rehman of Muzaffarnagar, Siddique of Malappuram, Masood Ahmed of Bahraich and Alam of Rampur, the police said.
