BJP has alleged that violence in Howrah was the result of the Trinamul Congress's conspiracy to win back the minority support following its debacle in the Sagardighi byelection and denied the chief minister's claim that the Ram Navami procession had deviated from its route on Thursday.

Union home minister Amit Shah spoke to Bengal BJP president Sukanta Majumdar on Friday evening about the situation in Howrah.

"I've told the honourable home minister Shri Amit Shah about whatever that has been happening in Howrah for the past two days and the incident in Dalkhola.... I'll write a letter seeking central intervention so that the real culprits are arrested. I've told him that the law and order in Bengal has been completely destroyed," Majumdar said in a video message to journalists.

Later, Majumdar tweeted a copy of his letter to Shah, in which he alleged that the Howrah incident was a result of a conspiracy hatched by Trinamul to use Ram Navami to win back minority voters after the ruling party lost the bypoll in Sagardighi, a constituency dominated by Muslims.

In a series of tweets dripping with communal overtones, Majumdar blamed Mamata Banerjee and her "politics of appeasement" for what had happened in Howrah. "Mamata didi's appeasement of a particular community knows no bounds. Spreading lies to blame the innocent victims themselves is the best your government can do. Shameless! Spineless!" one of his tweets read.

Top BJP leaders made repeated attempts throughout Friday to negate Mamata's claims that the procession in Howrah had taken an unauthorised route to deliberately create a ruckus.

BJP's Bengal co-minder Amit Malviya tweeted the picture of a document which he claimed was the proof of permission for the route the rally had taken. However, the content of the letter, undersigned by one Indra Deo Dubey, a Viswa Hindu Parishad worker, showed that it was written to the police commissioner to inform him about the route planned for the procession and sought his permission.

A stamp on the letter on behalf of the Howrah police showed that it was received by the law enforcers. It wasn't clear from the letter whether the police had granted or denied permission for the route.

Leader of the Opposition Suvendu Adhikari also blamed the alleged incompetence of Mamata's administration and said the chief minister was lying when she said the procession had taken an unauthorised route.

Adhikari on Friday filed a public interest litigation before Calcutta High Court for an NIA probe into the Howrah incident and immediate deployment of central forces. The matter will be heard on Monday.

"These clashes at PM Busty in Howrah's Shibpur were orchestrated by Trinamul's local councillor Shamim Ahmed. He did all this," Adhikarisaid.

"The perpetrators used petrol bombs to attack the processions. Clearly, the incidents have direct links with anti-national forces. This is why it is a fit case for NIA investigation."

Shah talks to Bose

Shah also spoke to governor C.V. Ananda Bose and took stock of the law and order in Howrah. "The governor is said to have provided details relating to the violence and the current situation (to Shah),” a Union home ministry official said.