A Basque radical has been sentenced to a year in prison for saying the King of Spain was "in charge of torturers".
Arnaldo Otegi spoke out against a visit by King Juan Carlos
Arnaldo Otegi, spokesman for the banned Basque nationalist party Batasuna, was charged with slandering King Juan Carlos during a 2003 news conference.
The Supreme Court's decision overturns a ruling by the Basque Superior Tribunal, which cleared Otegi in March on grounds of freedom of expression.
Batasuna was banned for allegedly being part of the Basque militant group Eta.
The slander charges related to a visit to the Basque region by the King of Spain in 2003.
Otegi told a news conference that the King was "chief of the Spanish army, that's to say, the person responsible for the torturers, who favour torture and impose his monarchic regime on our people through torture and violence".
Otegi later said that he had not intended to slander the king, and his criticism was directed at those who commit torture and not him personally, El Mundo newspaper reports.
Otegi faces an appeal at the Supreme Court later this month against a 15-month conviction for defending terrorism. He has previously spent four years in jail for kidnapping.