We study logarithmic operators in Coulomb gas models, and show that th
ey occur when the ''puncture'' operator of the Liouville theory is inc
luded in the model. We also consider WZNW models for SL(2,R), and for
SU(2) at level 0, in which we find logarithmic operators which form Jo
rdan blocks for the current as well as the Virasoro algebra. (C) 1998
Published by Elsevier Science B.V.