Two people were arrested on Thursday, while Union Minister Ajay Mishra's son was asked to appear before police in Lakhimpur Kheri violence case.
In the incident, eight people including four farmers were killed.
Ashish Mishra, the minister’s son who was booked for murder, has been asked to present himself before police at 10 am on Friday, a notice said.
Police identified the two arrested men as Luvkush of Banbirpur village and Ashish Pandey of Nighasan tehsil.
They were earlier being questioned by police.
Four of the eight people who died on Sunday were farmers, allegedly knocked down by a vehicle carrying BJP workers.(With PTI inputs)