An apparatus for and a method of monitoring multiphase fluid flow passing within a pipe is provided. The method includes the steps of: a) providing a flow pressure value and a flow temperature value for the multiphase fluid flow within the pipe; b) sensing the fluid flow with a fluid flow meter operable to be attached to an exterior of the pipe, the flowmeter including a spatial array of at least two sensors disposed at different axial positions along the pipe, and producing flow velocity signals indicative of a velocity of the fluid flow traveling within the pipe; c) selectively injecting at least one tracer into the fluid flow passing within the pipe, at a known injection flow rate and concentration; d) sensing a sample of the fluid flow for the tracer, and producing tracer concentration signals indicative of the concentration of the tracer in the fluid flow; and e) determining one or more of a gas component flow rate, an oil component flow rate, and a water component flow rate, using one or more of the flow pressure value, the flow temperature value, the flow velocity signals, and the tracer concentration signals.