Dev's approval for diplomat spies unlikely
I cannot envisage de Valera even contemplating putting Irish diplomats in such a compromising and illegal position, not to speak of putting their lives in danger, which could so easily be the case in the then war-time conditions. In any event, it would be most unlikely that the diplomats involved would give their consent to this harebrained scheme.
I have trawled through Tim Pat Coogan's biography of de Valera, in which he treats this period in some detail. However, I can find no mention of the above claim.