  We investigate the derivation of reggeon transition vertices from Lipatov's
gauge invariant effective action for high energy processes in QCD. In
particular we address the question of longitudinal integrations in order to
reduce the vertices into the required purely transverse form. We explicitly
derive the BFKL-kernel and verify vanishing of the 2-to-3 reggeon transition
vertex. First results on the derivation of the 2-to-4 reggeon transition vertex
are discussed.
