  We show that the diffeomorphism anomaly together with the trace anomaly
reveal a chiral Virasoro algebra near the event horizon of a black hole. This
algebra is the same irrespective of whether the anomaly is covariant or
consistent, thereby manifesting its universal character and the fact that only
the outgoing modes are relevant near the horizon. Our analysis therefore
clarifies the role of the trace anomaly in the diffeomorphism anomaly approach
\cite{wilczek, isowilczek, shailesh, shailesh2, sunandan, sunandan10, rabin10}
to the Hawking radiation.
