Disclosed is a leakage detection system (200) and a leakage detection method for detecting leakage in a gas supply system (10′) comprising a gas source (11; 12) connected to a gas delivery module (14) by a pipeline. The leakage detection system (200) comprises a flow meter (113) connectable along the pipeline remotely from an inlet of the gas delivery module (14); and a detection module (110) configured to receive signals representing a measured flow rate from the flow meter (113), and to compare the measured flow rate (115) to a stored leakage-free reference value (116) to detect an increase in flow rate in the presence of a leak. A flow resistance between the detection module (110) and an outlet of the gas delivery module (14) amplifies the increase in flow rate in the presence of a leak. The system (200) may comprise a flow rate elevation system (121) connectable between the gas source (11; 12) and the flow meter (113) for temporarily increasing the flow rate in the pipeline.