A method of detecting and locating a fluid leak in a fluid distribution network that comprises a plurality of ultrasonic fluid meters , each ultrasonic fluid meter comprising an upstream transducer situated beside the fluid distribution network and a downstream transducer situated beside an installation that is fed with fluid by said fluid distribution network, the method comprising, for each ultrasonic fluid meter , the following steps: · acquiring or evaluating noise levels, each associated with a respective different detection period, each noise level being representative of a level of a leakage noise signal contained in measurement samples coming from measurements taken by the transducer of said ultrasonic fluid meter during the associated detection period; · comparing each noise level with a predetermined noise threshold; · detecting that a fluid leak is present in the proximity of the ultrasonic fluid meter on detecting at least a predetermined number of successive noise levels that are greater than the predetermined noise threshold and that correspond to detection periods that are spaced apart in time by at least a predetermined duration; the method being such that the measurement samples used for performing the method comprise first measurement samples that come from measurements taken by the downstream transducer of said ultrasonic fluid meter or second measurement samples that come from measurements taken by the upstream transducer of said ultrasonic fluid meter or the first measurement samples and the second measurement samples, the method further comprising the step, when said method is performed with the first measurement samples and a leak is detected, of locating said leak as being in the fluid distribution network upstream from said ultrasonic fluid meter or the method further comprising the step, when said method is performed with the second measurement samples and a leak is detected, of locating said leak as being in said installation downstream from said ultrasonic fluid meter . · acquiring or evaluating noise levels, each associated with a respective different detection period, each noise level being representative of a level of a leakage noise signal contained in measurement samples coming from measurements taken by the transducer of said ultrasonic fluid meter during the associated detection period; · comparing each noise level with a predetermined noise threshold; · detecting that a fluid leak is present in the proximity of the ultrasonic fluid meter on detecting at least a predetermined number of successive noise levels that are greater than the predetermined noise threshold and that correspond to detection periods that are spaced apart in time by at least a predetermined duration; the method being such that the measurement samples used for performing the method comprise first measurement samples that come from measurements taken by the downstream transducer of said ultrasonic fluid meter or second measurement samples that come from measurements taken by the upstream transducer of said ultrasonic fluid meter or the first measurement samples and the second measurement samples, the method further comprising the step, when said method is performed with the first measurement samples and a leak is detected, of locating said leak as being in the fluid distribution network upstream from said ultrasonic fluid meter or the method further comprising the step, when said method is performed with the second measurement samples and a leak is detected, of locating said leak as being in said installation downstream from said ultrasonic fluid meter . <EOS>