Exact non-abelian target space duality

We investigate non-abelian target space duality via non-abelian gaugings of WZNW models. When the gauged group is semisimple we are able to present exact formulae for the dual conformal field theory, for all values of the level k. Applying the results to non-abelian target space duality in string theory we show that the standard formulae are quantum mechanically well defined in the low energy limit if the gauged group is semisimple, showing that non-abelian duality is a true symmetry of string theory in these cases.