  It is shown that the master equation of the affine-Virasoro construction on
the unitary affine algebra naturally emerges in the fusion algebra of the
nonunitary level $k$ WZNW model. Operators corresponding to solutions of the
master equation are suitable for performing one-parametrical renormalizable
perturbation around the given conformal nonunitary WZNW model. In the large
$|k|$ limit, the infrared fixed point of the renormalization group beta
function is found. There are as many infrared conformal points as
$\frac{1}{2}N(N+1)$, where $N$ is the total number of solutions of the master
equation.
