A method and apparatus are provided for biometric authentication of a user to be authenticated, from among a plurality of users, with an authentication system storing a set of pieces of reference biometric data, each associated with one of the users. The method includes providing, by the user to be authenticated, a piece of biometric authentication data by a device for obtaining biometric data from a transactional terminal. A subset of the set of pieces of reference biometric data stored by the authentication system is searched for a piece of reference biometric data corresponding to the user to be authenticated as a function of the piece of biometric authentication data. The step of searching includes filtering the pieces of reference biometric data as a function of: a base station of a mobile communications network; and a set of mobile devices for which a connection indicator is activated for the base station. The transactional terminal is substantially near a zone of coverage of the base station.