The Kolkata Municipal Corporation on Friday started pulling down a tilted, under-construction structure in Tangra from where a demolition squad of the civic body had to retreat a day before in the face of resistance from those who had booked flats in the illegal building.

In neighbouring Bidhannagar, residents of an illegal building locked themselves in forcing a demolition squad sent by the civic body there to return without starting work on Friday.

Firhad Hakim, the mayor of Calcutta and the state’s urban development minister, said in the evening that the law would take its course and illegal structures would be pulled down.

Hakim issued a veiled warning to those stopping civic teams that the act was an offence and they could be booked for preventing government servants from discharging duty. He, however, quickly added that the government would not do so.

Citing a Supreme Court order, Hakim said no building would get water, electricity and drainage connections without a completion certificate from the civic body. The certificate cannot be issued if a structure is illegal.

Two buildings on Christopher Road in Tangra have tilted dangerously towards each other. One of the buildings, a five-storey structure with light green exterior paint, has families living there for over a year.

The other is the six-storey structure that is being pulled down.

KMC officials said both buildings are illegal as the civic body had not issued any permit for them.

A structural engineer hired by the KMC has suggested that the structure under construction be pulled down first to determine whether the other can be retained.

When a KMC team reached the spot on Thursday, many people resisted the demolition. Those who had booked flats in the building wanted alternative accommodation.

On Friday, the KMC team went back and started the demolition. KMC sources said those who booked flats in the building were told that the civic body could have filed police complaints against them but chose not to do so.

Sources said the structural engineer would determine whether the entire building would be pulled down.

In Bidhannagar, portions of an illegal six-storey building were pulled down on Thursday. The civic body’s demolition team, however, was not allowed to enter the building on Friday.

A court has ordered the demolition of the building.

Bidhannagar mayor Krishna Chakraborty said: “When our team went to the spot on Friday, they were not allowed entry. Later, the residents told us they have appealed against the court’s earlier order. We will wait till the court gives an order based on the appeal.”

List of companies

The KMC will soon invite “expression of interest” from companies specialising in fixing tilted buildings. Hakim had said there were 30 tilted buildings in Calcutta.

“We will verify the credentials of the companies that will submit applications with Jadavpur (University) or (IIT) Kharagpur. If the experts tell us that the companies are qualified to do the work, we will certify them as companies empanelled by the KMC to fix problems in titled buildings,” the mayor said.