Natural Selection Foods, the Californian firm that found itself at the centre of a nationwide E.coli outbreak last month has been forced to lay off 164 employees.

Most of the staff that have been let go were seasonal workers at the San Juan Bautista firm’s plant, who had expected to leave when the growing season ends next month.

NSF played a central role in the fatal outbreak of E.coli linked to contaminated spinach, which has led to a 70 per cent drop in sales of bagged salads since authorities began warning consumers not to eat bagged spinach September 15.