We consider N=4 SU(2)xU(1) gauged supergravity on asymptotically-AdS_5
backgrounds. By a near-boundary analysis we determine the boundary-dominant
components of the bulk fields from their partially gauge-fixed field equations.
Subdominant components are projected out in the boundary limit and we find a
reduced set of boundary fields, constituting the N=2 Weyl multiplet. The
residual bulk symmetries are found to act on the boundary fields as
four-dimensional diffeomorphisms, N=2 supersymmetry and (super-)Weyl
transformations. This shows that the on-shell N=4 supergravity multiplet yields
the N=2 Weyl multiplet on the boundary with the appropriate local N=2
superconformal transformations. Building on these results we use the AdS/CFT
conjecture to calculate the Weyl anomaly of the dual four-dimensional
superconformal field theories in a generic bosonic N=2 conformal supergravity
background.Comment: 23 pages; to appear in JHE