In its complaint at the Jorasanko police station in north Kolkata on Sunday, the BJP has demanded the arrest of an imam of a central Kolkata mosque and others.
The imam, on Saturday, had issued a fatwa against Prime Minister Narendra Modi and announced an award of Rs 25 lakh to anyone who shaved his hair and beard and blackened his face.
A Trinamool MP, Idris Ali, was seated next to the cleric, Imam Nurur Rehman Barkati when the fatwa was announced on Saturday.
The cleric is unrepentant. He has often been seen on stage with Mamata Banerjee, chief minister of West Bengal.
"Why should I apologise for the fatwa ? 125 people have died standing in lines at banks because of demonetisation and there is no apology from the PM," he says, adding, "The fatwa is in place. I am also not scared. What is an FIR against and imam? What have I done?"
But the BJP is not passing up this chance to attack the Trinamool chief. National secretary Rahul Sinha said at a press conference on Monday, "Mamata Banerjee is behind the fatwa. The imam and the TMC MP with him should be arrested. If they are not, we will go to court."
Mr Ali, however, would not comment on the fatwa, something that has outraged many Hindus and Muslims alike in Kolkata and beyond. No comments either from a senior Trinamool minister Subrata Mukherjee.
"I don't want to comment on the issue. The party has not discussed it," he said.
Another Muslim cleric, the Imam of Furfura sharif, Toha Siddiqi, has criticised Imam Barkati's comments saying, "He should not fan flames when there is a fire. He should pour water. I don't believe Mamata Banerjee would support such a comment."
Imam Barkati had earlier issued a fatwa against Bengal's BJP chief for questionable comments against Mamata Banerjee.
No action was taken against him then.