  A method for implementing non-Abelian duality on string backgrounds is given.
It is shown that a direct generalisation of the familiar Abelian duality
induces an extra local symmetry in the gauge invariant theory. The non-Abelian
isometry group is shown to be enlarged to a non-semi-simple group. However,
upon eliminating the gauge fields to obtain the dual theory the new algebra
does not close. Therefore the gauge fixing procedure becomes problematic. The
new method proposed here avoids these issues and leads to a dual theory in the
proper sense of duality.
