Who among the following is responsible for access control to an airport?

In the Indian civil aviation security framework, the Bureau of Civil Aviation Security (BCAS) acts as the regulatory authority that defines security standards and policies. The actual operational responsibility for access control—which involves regulating the entry of passengers, staff, and vehicles into the terminal and sterile areas—lies with the Airport Security Unit (APSU) or the Aviation Security Group (ASG). In most major Indian airports, the Central Industrial Security Force (CISF) is designated as the ASG. While the Airport Operator (such as AAI or private entities) is responsible for providing the necessary security infrastructure like perimeter fencing and lighting, the physical task of verifying credentials and managing access points is the mandate of the APSU/ASG personnel.