Clashes broke out between supporters of Prime Minister Narendra Modi and an opposition leader in the key Indian city of Kolkata on Wednesday, before the final round of the national election.
Dozens of people were arrested in street battles late on Tuesday that forced Amit Shah, president of the ruling Bharatiya Janata Party, to leave an election rally under police guard, reports said.
A statue of renowned Bengal reformer Ishwar Chandra Vidyasagar was destroyed and a college named after him ransacked in the clashes, which the BJP and rival Trinamool Congress blamed on each other.
There has been repeated violence in the state during the six-week election that ends on Sunday.
Mr Modi's BJP hopes to capture many of the state's 42 parliamentary seats from the TMC to compensate for losses predicted in other regions.
The BJP accused West Bengal's Chief Minister, Mamata Banerjee, of orchestrating attacks on a roadshow by Mr Shah through Kolkata.
"Has Bengal acquired a government of gangsters? The attack on Amit Shah's peaceful rally by TMC is deplorable," Finance Minister Arun Jaitley said on Twitter.
Ms Banerjee, who called a protest rally for Wednesday, hit back by accusing Mr Shah of acting like a "god".
Indian political observers say the aggressive campaign by Mr Modi's party against the TMC in West Bengal has made it the state with the most bitter contests in the election.
Mr Modi won a landslide victory in 2014 but is expected to lose his overall majority.
A good performance in West Bengal would significantly improve his chances of a second term.
