A method and system processes location data associated with a transaction in an electronic transaction processing system. The system comprises at least one point of sale terminal, such as a merchant terminal or ATM terminal, and at least one cardholder mobile terminal, each terminal being connected to a network and associated with a same electronic transaction. Data representative of the geographical location of the at least one point of sale terminal and data representative of the geographical location of the at least one cardholder mobile terminal is also obtained. The respective positional data of the terminals is compared, and an alert message is communicated over the network if the comparison indicates that the terminals are not located within a predetermined proximity to one another. The transaction can be authorised or rejected based on the position of the cardholder at the time to the transaction.