12345 Kolkata: Airport authorities have enhanced surveillance, both physical and digital, to ensure absolute security.Technicians on Saturday checked nearly 1,000 CCTV cameras on the airport premises, including those on the city side, air side and within the terminal building, to make sure each of them worked and provided a clear feed of images."We ensured 100% serviceability of CCTVs at the Kolkata airport so that all critical areas are under surveillance," an official said.CISF, which guards the airport and checks flyers as well as airport and airline staff and other service providers entering the airport, stepped up patrolling. Mobile quick response teams were also activated to meet emergency situations. The number of CISF personnel at the airport has been increased from 1,400 to 1,600, and efforts are underway to get more. The sanctioned strength of the force at the airport is around 2,300. CISF has deployed more plainclothes personnel for intelligence gathering and checking both passengers and airline ground staff, service providers, like refuelling companies, airline caterers and baggage handlers. Security and surveillance of the domestic and international cargo facilities at the airport have been enhanced as well. "Aircraft and catering service trucks are being searched to ensure only authorised items are put on aircraft," said an officer, adding airlines had been asked to station more security officers outside parked aircraft.Sources said the deployment of extra CISF personnel for city-side checks and vigil around the perimeter wall could push back the rollout of DigiYatra in the domestic-to-domestic transfer in the terminal, supposed to start operations in the first half of May.CISF and the airport also urged Bidhannagar Police to enhance security outside the airport's wall. The Bengal STF has arrested four persons and recovered weapons and ammunition from an SUV near the airport. Police claimed it was a gang involved in interstate weapons trafficking.