The fuelling of plasmas by shallow frozen pellets with simultaneous mitigation of edge-localized modes (ELM) by external magnetic perturbation is demonstrated on the MAST tokamak. In these plasmas post-pellet particle loss is dominated by ELMs. It is shown that the size of post-pellet ELMs can be controlled by external magnetic perturbations. Post-pellet ELMs remove particles from a large part of the pellet deposition zone including the area with positive density gradient. The mechanism explaining this peculiarity of particle loss is suggested.