Five men were arrested on Sunday in connection with the attack on Trinamool Congress national general secretary Abhishek Banerjee during his visit to Sonarpur on Saturday.
Investigators identified the accused after examining video footage of the incident, sources said.
The accused have been identified as Akash Gayen, Kajal Das, Debashis Dutta, Tapan Maity and Nirmalya Sengupta. They are residents of Ward No. 9 of the Rajpur-Sonarpur municipality.
A case has been registered against them for alleged assault, unlawful assembly, wrongful restraint, verbal abuse and intentional insult with intent to provoke breach of peace.
Sources in the area said some of the men arrested in connection with the attack were Trinamool supporters.
Some others seen in the footage have also been identified as Trinamool functionaries, sources said.
Sources said Akash Gayen is known to be an acquaintance of former Sonarpur South MLA Arundhati Maitra (Lovely). Repeated phone calls and a text message sent to Maitra seeking her response to the allegations went unanswered.
Gayen’s mother, Shankari, told reporters her son was a Trinamool functionary but denied knowledge of her son having attacked Abhishek.
A resident of Sonarpur said most of the people who were active Trinamool functionaries have switched to the BJP.
At least one of the five men arrested is known to be an “old BJP” functionary.
All five were produced before the Baruipur court on Sunday and sent to a day's judicial custody. They would be produced before the court again on Monday.
According to the police, Sonarpur police station has initiated a suo motu case over the incident.
The incident occurred when Abhishek visited Sonarpur to meet the family of a Trinamool worker who was allegedly killed in post-poll violence. As he entered the area on Saturday afternoon, a section of residents staged a protest, hurled eggs, shoes and stones at him and beat him up, while raising slogans against him.
Banerjee had to wear a cricket helmet with a visor to protect himself from the projectiles. During the ensuing scuffle, his shirt was ripped open.
He nevertheless met the bereaved family and remained there for some time before being escorted out by the police and central forces.
Banerjee later alleged that the attack was pre-planned and orchestrated by the BJP. He threatened legal action against those responsible. The BJP claimed it was a “spontaneous" outpouring of people's anger.
The Trinamool Congress has accused the police of deliberately delaying their response, allowing the unrest to escalate. Following the attack, Banerjee was taken to a private hospital in Calcutta.
Former chief minister Mamata Banerjee later visited him and claimed that he had developed a blood clot in his chest following the assault. She also alleged that the hospital had refused to admit him for treatment.
The attack has drawn reactions from several leaders of the INDIA bloc, including Rahul Gandhi and Arvind Kejriwal, who condemned it and expressed solidarity with the Trinamool leader.