The navy has prohibited the use of drones within 3km of the perimeter of all naval installations in Bengal.

“All individuals or civil agencies are prohibited from flying any such non-conventional aerial objects, drones and UAVs within these zones,” read an order issued by the naval-officer-in charge of Bengal.

The places in the state where naval installations are located include Calcutta, Barrackpore and Diamond Harbour.

Officers of the eastern naval command said the order meant that in Calcutta no drones would be allowed to fly over or around Fort William, second Hooghly bridge and Hastings, which is home to the naval base, INS Netaji Subhas.

Though Fort William is an army installation, it figures on the list of no-fly zones because it is within 3km of Hastings.

“The order comes into immediate effect and all state and central agencies concerned in Bengal have been given copies of the directive,” said an officer of the eastern naval command. “If any unmanned aerial vehicle is found to violate the directive, the naval installation can confiscate or destroy it without prior approval.”

Since the twin blasts at the Jammu airbase on June 27, which are suspected to have been carried out by drones, intelligence agencies have been instructing naval commands to step up surveillance to thwart any suspected attack using UAVs.

Naval officers said a clearance from the security office of the navy at Hastings had to be obtained a week in advance before flying UAVs or drones in the areas where those were banned.

In March 2019, CISF personnel at Victoria Memorial had arrested a Chinese national for flying a drone over the monument.