Multichannel intramuscular EMG (iEMG) recordings provide information on motor neuron behaviour, muscle fiber (MF) innervation geometry and, recently, have been proposed as means for establishing human-machine interfaces. Objective: in order to provide a reliable benchmark for computational methods applied to such recordings, we propose a simulation model for iEMG signals acquired by intramuscular multi-channel electrodes. Methods: we propose a number of modifications to the existing iEMG simulation methods, such as farthest point sampling for more uniform motor unit in-nervation centers distribution in the muscle cross-section, fiber-neuron assignment algorithm, motor neuron action potential propagation delay modelling and a linear model for multichannel recordings simulation. The proposed approach is also extended to gradually shifting (scanning) electrodes. Results: we provide representative applications of this model to the validation of methods for the estimation of motor unit territories, and for iEMG decomposition. Moreover, we extend this model to a full multichannel iEMG simulator using classical linear EMG modelling and existing approaches to the generation of motor neuron discharge sequences. Conclusions: the obtained simulation model provides physiologically accurate MUAPs across entire motor unit territories and for various electrode configurations. Significance: it can be used for the development and evaluation of mathematical methods for multichannel iEMG processing and analysis.