His salary of £415,000 was cited anonymously in Charity Trends 2005 last week. The Opera House refuses to discuss salaries and declined to identify Pappano.
The salary - which is nearly twice that of Cabinet Secretary Andrew Turnbull, who earns £216,000 a year - was said by Debra Allcock Tyler, chief executive of the Directory of Social Change, to reflect badly on the sector.
But other commentators pointed out that major arts institutions that are also charities cannot survive without paying competitive salaries to world class artists, who should not be considered charity employees in the usual sense.
Pappano, born in London of Italian parents, has conducted most of the world's major orchestras and has been music director at the Opera House since 1999.
In October this year he is due to move to a post at the prestigious Accademia Nazionale di Santa Cecilia in Rome, founded in the 16th century.
Our report last week incorrectly stated that the Royal Opera House received £21.7m from the National Lottery in 2003/04. In fact, it received no lottery funding that year. The figure was taken from Charity Trends, which has since issued a correction.