Ink was thrown at Bharatiya Kisan Union leader Rakesh Tikait during an event in Bengaluru on Monday.
Tikait claimed that no security was provided to him by the Bharatiya Janata Party in the state.
“This [ink attack] has been done in collusion with the government,” he said to ANI news agency.
The incident happened when Tikait was addressing a press conference on a sting operation in which a Karnataka farmers’ leader was allegedly caught asking for money.
About a dozen people barged into a press meet, according to NDTV.
Tikait was one of the faces of the farmers’ movement against the now repealed agricultural laws.