Uncountable locally free groups and their group rings

In this note, we show that an uncountable locally free group, and therefore every locally free group, has a free subgroup whose cardinality is the same as that of $G$. This result directly improve the main result in [T. Nishinaka,"Group rings of countable non-abelian locally free groups are primitive", Int. J. algebra and computation, 21(3)(2011), 409-431] and establish the primitivity of group rings of locally free groups.