The death of a hotelier after he was threatened, allegedly by a Trinamool Congress activist, sparked outrage on Tuesday with Bengal's opposition parties on Tuesday accusing the ruling party of "shielding the guilty" and urged Chief Minister Mamata Banerjee to rein in criminals.

Police have registered a case of unnatural death.

On the other hand, a Trinamool municipal councilor attributed the death to "tension" triggered by family issues.

Sumit Naha, who owned a lodge in Howrah, died following a heart attack at his residence at Baguiati in Kolkata's north eastern outskirts early Monday with his family alleging that he could not bear the incessant threats and intimidation by local Trinamool activists.

Naha's mother Manju claimed that her son was being threatened to withdraw a police complaint he had filed after his manager Ashish Manna was assaulted and threatened in the lodge by a gangster having links with the Trinamool.

The family in a police complaint has submitted CCTV footage which shows a gangster, claimed to be a Trinamool activist, assaulting the manager.

"This incident is a glaring example of the widespread extortion by Trinamool goons. Enjoying patronage of the ruling party, antisocial and criminals are wreaking havoc. On the other hand, the administration and the police have been rendered useless," state Bharatiya Janata Party president Rahul Sinha told media persons here.

Claiming that lawlessness in Bengal was rapidly increasing; Sinha blamed the administration and held Banerjee – who heads the home department – responsible.

Meanwhile, one of the councilor in Howrah municipality Debesh Saha of the Trinamool, rubbishing the involvement of his party-men, attributed Naha's death to tension related to his daughter's marriage three years back.

"All the talks of involvement of Trinamool people is false.. Naha died because of tensions that followed his daughter's marriage," said Saha.

Saha's claims have been strongly criticised by Naha's neighbours while leader of opposition and Marxist veteran Surjya Kanta Mishra accused the Trinamool of trying to suppress the truth.

"This is being done to suppress the truth, the ruling party, from top to bottom is trying to prevent the truth from coming out," Mishra said after visiting the bereaved family.

Naha's neighbours dubbed Saha's comments "atrocious".

Incidentally, Trinamool legislator from Howrah North Ashok Ghosh admitted that the man who assaulted Manna had links with his party.

"He is a Trinamool member, he was a unit president, its unfortunate," Ghosh said.

However, Agricultural Marketing Minister Arup Roy said the man caught assaulting had been expelled from the Trinamool in 2010.

While no arrest has been made in connection with the assault on the manager, Howrah Police Commissioner A.M. Ranade said police were on the lookout for the assaulter.

"Raids are being conducted, the man has fled. We are conducting a probe. We are taking all necessary legal action," he said.