Calcutta police commissioner Anuj Sharma has asked officers to be “very firm but polite” with citizens to ensure they stay indoors during the lockdown, police said.

Chief minister Mamata Banerjee had on Saturday announced an extension of the lockdown till April 30.

Drones will be used to keep a bird’s-eye view on densely populated areas in the city to ensure social distancing rules are followed, the police said on Sunday. Drones will act as a “deterrent” to lockdown violators, Sharma is learnt to have said.

“We should strictly maintain lockdown in all areas, especially in places that have reported positive cases. Unnecessary movement of people and vehicles should not be allowed,” an officer quoted the commissioner as saying.

“But access to essential commodities by the general public is to be ensured.

OCs should facilitate home delivery of essential goods and medicines… that will ensure people do not leave their homes unnecessarily.”

The officer said: “We were told to be very firm but polite. Unnecessary harassment of public has to be avoided.”

There have been several complaints across the state of police excesses on people who had stepped out of their homes to buy medicines or essential supplies. The police have been accused of stopping essential service providers from joining duty.

At least 12 cops in the Bengal police’s jurisdiction have been “closed” (a type of punishment) and departmental proceedings initiated against four of them.

There has been no such allegation in the city police’s area but it is the duty of the force to maintain restraint despite being firm on lockdown rules, a city police officer said.

City cops have been prosecuting people who fail to justify why they stepped out of their homes. The officer, however, said the biggest challenge lay in controlling people’s movement in lanes.

The drones are expected to play a vital role in monitoring densely populated pockets. There have been instances of residents of such pockets stepping out of their homes the moment a police patrol leaves the place.

“We can prevent such situations by keeping a close watch with the help of drones. The live feed will be monitored at Lalbazar. The moment such a thing is seen, the nearest police patrol will be sent to the spot,” an officer in Lalbazar said.

“People will have a fair idea that we can see them even when they cannot see us.”

On Sunday evening, cops on loudhailers asked residents of housing complexes along the Bypass not to loiter on the campus.

“We have been getting reports that residents of housing complexes have been stepping out of their homes. They are loitering on the complex premises without any restrictions,” an officer in Lalbazar said.

The number of checkpoints on roads will be increased in the next phase of the lockdown to ensure stricter prosecution of violators, the officer said.