Let λ be an infinite regular cardinal. It is proved, under the assumption of the Generalized Continuum Hypothesis, that any λ-accessible and λ-accessibly embedded subcategory K of a category of modules closed under direct sums gives rise to non-trivial κ-separable modules, for arbitrarily large regular cardinals κ ≥ λ, when some modules of K are not direct sum of λ-presentable modules (namely, those modules which are totally ordered λ-directed colimits of λ-presentable modules). In particular, it is shown that any ring R that is not left pure-semisimple has non-trivial λ-separable left modules for arbitrarily large regular cardinals λ. These results extend previous constructions by Corner, Griffith, Hill, Eklof, Shelah and Huisgen-Zimmermann. We point up that κ-separable modules satisfy certain generalized Mittag-Leffler conditions.