An electronic access control device (1) includes a radio communication module (11) for wireless data exchange in a first radio frequency band with a mobile device (2) over a direct wireless communication link (3). The access control device has a controller (12) connected to the wireless radio communication module for generating an access control signal using an access key received from the mobile device. The electronic access control device further includes a proximity detector (13) for detecting a mobile device in defined proximity (P), using a radio frequency in a second radio frequency band, different from the first radio frequency band. The controller is connected to the proximity detector and controls the radio communication module to establish the direct wireless communication link with the mobile device, only if the mobile device is detected in defined proximity of the electronic access control device.