  We investigate the nature of power corrections and infrared renormalon
singularities in large $\beta_0$ approximation. We argue that the power
correction associated with a renormalon pole singularity should appear at O(1),
in contrast to the renormalon ambiguity appearing at $O(1/\beta_0)$, and give
an explanation why the leading order renormalon singularities are generically
poles.
