A method of operating a smartcard (102; 202) having a biometric sensor (130; 230) embedded therein, the method comprising: operating the smartcard (102; 202) in a normal mode of operation; detecting possible fraudulent use of the smartcard (102; 202); and responsive to detection of the possible fraudulent use of the smartcard (102; 202), operating the smartcard (102; 202) in a restricted mode of operation in which use of the smartcard (102; 202) is restricted but not prevented, wherein the restriction comprises at least one of: permitting a bearer of the smartcard to perform a first action after authorisation that they would be permitted to perform in the normal mode of operation, and not permitting the bearer to perform a second action after authorisation that they would be permitted to perform in the normal mode of operation; requiring a higher authorisation confidence score before permitting the bearer to perform an action than would be required to perform the same action in the normal mode of operation; requiring the bearer to pass a primary authorisation step and a secondary authorisation step, both performed by the smartcard, before permitting the bearer to perform an action, wherein the secondary authorisation step would not be required to perform the same action in the normal mode of operation; and preventing authorisation of the bearer using the biometric sensor when authorising the bearer by the smartcard. operating the smartcard (102; 202) in a normal mode of operation; detecting possible fraudulent use of the smartcard (102; 202); and responsive to detection of the possible fraudulent use of the smartcard (102; 202), operating the smartcard (102; 202) in a restricted mode of operation in which use of the smartcard (102; 202) is restricted but not prevented, wherein the restriction comprises at least one of: permitting a bearer of the smartcard to perform a first action after authorisation that they would be permitted to perform in the normal mode of operation, and not permitting the bearer to perform a second action after authorisation that they would be permitted to perform in the normal mode of operation; requiring a higher authorisation confidence score before permitting the bearer to perform an action than would be required to perform the same action in the normal mode of operation; requiring the bearer to pass a primary authorisation step and a secondary authorisation step, both performed by the smartcard, before permitting the bearer to perform an action, wherein the secondary authorisation step would not be required to perform the same action in the normal mode of operation; and preventing authorisation of the bearer using the biometric sensor when authorising the bearer by the smartcard. permitting a bearer of the smartcard to perform a first action after authorisation that they would be permitted to perform in the normal mode of operation, and not permitting the bearer to perform a second action after authorisation that they would be permitted to perform in the normal mode of operation; requiring a higher authorisation confidence score before permitting the bearer to perform an action than would be required to perform the same action in the normal mode of operation; requiring the bearer to pass a primary authorisation step and a secondary authorisation step, both performed by the smartcard, before permitting the bearer to perform an action, wherein the secondary authorisation step would not be required to perform the same action in the normal mode of operation; and preventing authorisation of the bearer using the biometric sensor when authorising the bearer by the smartcard.