My stalwart spanking spies alerted me to the presence of a brutal and dramatic naked belt spanking scene in the 2001 French drama Les Jolies Choses. (The English title is Pretty Things.) My spies were not wrong:
"...the girls are prepared in the reformatory’s punishment room, naked, lying on their backs on special benches, bound with their legs spread above their heads, shamefully showing the two holes usually hidden..."