  The solutions of the sl_N Knizhnik-Zamolodchikov(KZ) equations at level 0 are
studied. We present the integral formula which is obtained as a quasi-classical
limit of the integral formula for form factors of the SU(N) invariant Thirring
model due to F. Smirnov. A proof is given that those integrals satisfy sl_N KZ
equation of level 0. The relation of the integral formulae with the chiral
Szego kernel is clarified. As a consequence the integral formula with the
special choice of cycles is rewritten in terms of the Riemann theta functions
associated with the Z_N curve. This formula gives a generalization of Smirnov's
formula for sl_2.
