1. A method of protecting physical access having a plurality of sensor systems ( 1. 4 , 1. 5 , 1. 6 ), the method being aimed at discriminating valid access from a fraudulent attempt at access, comprising the following steps: in a preliminary phase: determining at least one set of parameters issuing from sensor systems including at least one set of parameters issuing from at least two different systems ( 6. 1 ); determining by learning, for each set of parameters and for each type of fraud envisaged, a class of values of the parameters in the set corresponding to this type of fraud for this set of parameters ( 6. 2 ); during access: determining sets of values formed by the values taken by each parameter of each set of parameters for this access ( 6. 3 ); determining a probability of fraud associated with each type of fraud for each set of parameters, according to the set of values determined during this access and the class corresponding to the type of fraud for this set of parameters ( 6. 4 ); determining a global probability of fraud associated with the access according to the probabilities of fraud obtained for each set of parameters and for each type of fraud ( 6. 5 ).