North 24 Pargana district's Bhatpara assembly seat, which fell vacant after Trinamool Congress MLA Arjun Singh's defection to the BJP nearly two months ago, topped the chart of violence as the workers of both the parties frequently clashed with each other with crude bombs.

Singh's son Pawan Kumar Singh has been fielded by the BJP while Trinamool has fielded Saradha and Narada scam accused leader Madan Mitra.

The constituency's Ghoshpara and Kankinara areas turned into a battleground.

The agitators also ransacked several police vehicles and attacked the personnel when they arrived at the spot. The Rapid Action Force rushed to the spot and carried out baton charge to disperse the mob.

A crude bomb was hurled in north Kolkata's Posta area at around 12.30 p.m., striking panic among the voters. However, no one was injured in the incident.

Earlier in the day, BJP's Kolkata North candidate and former state chief Rahul Sinha was allegedly pelted with stones while coming out of a polling station in Park Circus area. A cameraperson of a local news channel sustained head injury.

Sporadic violence was reported in Diamond Harbour Lok Sabha seat, where West Bengal Chief Minister Mamata Banerjee's nephew and Trinamool MP Abhishek Banerjee is seeking a second term.

The vehicle of the Bharatiya Janata Party's (BJP) candidate Nilanjan Roy was allegedly vandalised in Budge Budge after he reached a polling booth hearing reports of proxy voting by the state's ruling party.

Situation became tense in Diamond Harbour's Minakha after BJP activists were allegedly intimidated and beaten to stop them from casting their votes. Central forces, however, reached the spot and escorted the voters to the polling booth.

Another BJP candidate Anupam Hazra (Jadavpur) and a local saffron party leader were attacked and the latter's car was damaged allegedly by Trinamool workers outsde Ward No. 109 of the Kolkata Municipal Corporation.

Meanwhile, Trinamool candidate Kakoli Ghosh Dastidar in some booths in Barasat constituency's Rajarhat-Newtown area, accused central forces of attacking their workers, vandalising booth offices and influencing the voters to vote for BJP.

West Bengal Chief Minister Mamata Banerjee also claimed that the BJP workers and CRPF personnel were "torturing common people" in various parts of the state.