Over a thousand Congress workers including the party's state unit chief Bhupesh Baghel were detained in Chhattisgarh on Saturday as they were heading for Janjgir-Champa district to show black flags to Prime Minister Narendra Modi. The opposition party had said it would oppose Modi's rally, to protest against the lathi-charge on Congress workers by police in Bilaspur town of the state on September 18. While 489 Congress workers including Baghel were stopped in Balodabazar district, 676 party workers including senior leader T S Singhdeo were held in Bilaspur district, police said. Baghel and others were proceeding to Janjgir-Champa from Raipur when they were intercepted by police near Katgi, Balodabazar Superintendent of Police Prashant Agrawal said. Durg MP Tamradhwaj Sahu, Rajya Sabha member Chhaya Verma, former MLA Ravindra Choubey and seven sitting Congress MLAs were among those detained for violating the orders prohibiting unlawful assembly, the officer said. Singhdeo and other Congress workers were arrested from separate places in Bilaspur, another official said. All of them were released later, police said. Seven Congress workers were injured in a lathi-charge by police following a protest by party workers outside Urban Administration Minister Amar Agrawal's house in Bilaspur four days ago. Subsequently, the BJP government ordered a magisterial probe into the incident and shunted out a senior police official. However, the Congress had said its workers would show black flags to Modi during his visit to Janjgir-Champa as their demand of registration of FIR against the concerned police officer and enquiry by a high court judge was not met. Modi addressed a farmers' rally at Janjgir on Saturday.