According to the Associated Press, a spokesperson for the court would not say why the royal couple had canceled plans to attend the premiere of the production on February 11. But the newspaper Expressen reported that they changed their minds after speaking with Palme's son about the staging.
Un ballo in maschera originally depicted the real-life murder of Swedish king Gustav III at a masquerade ball in 1792, but before its premiere in 1859 Italian censors forced Verdi to move the action to colonial America.
In the new Malm‹ production, directed by Peter Oskarson, the central character is a prime minister, rather than a king, and he is twice called Olof.
Marten Palme, the son of the former prime minister, reportedly told the king and queen that it was in bad taste to stage the production so close to the 20th anniversary of his father's murder, which took on February 28, 1986. The murder has never been solved.