Seven police personnel suffered injuries, allegedly, after being assaulted by workers of the Peermade Tea Company at Cheenthalar on Tuesday.
The company which had remained closed for over a decade had recently been re-opened.
The assault resulted from labour rest in the estate between CITU and other employee unions, police said.
M N Ramesh, DySP, Kattapana and Ashraf, A Civil Police Officer (CPO) of Peermedu police station suffered fractures on their hands, police said.
ASI P A Joseph of Upputhara police station, CPO Selvan, George, constables Sajeev Antony and Manju were others who sustained injuries.
The injured are being treated at a private hospital at Kattapana. Cases have been registered under different sections against 75 identifiable people, police said.
The incident occurred on Tuesday evening when the a police team went to the estate after complaints were lodged against supporters of CITU, that they destroyed tea leaves picked by workers of other unions, police said.
A complaint had already been lodged against some people for pouring kerosene over bags of tea leaves, which were being taken in vehicle to a tea factory from the estate making them useless, police said.