Prosecutors say Otegi in effect praised terrorism, which is a crime in Spain, during the speech at the rally.


Otegi's lawyer said the politician was exercising his right to free speech, but a five-judge panel at the supreme court ruled unanimously against the appeal.


The case was returned to the national court, who issued the original guilty verdict, who chose not suspend Otegi's sentence.


The national court official said Otegi was arrested while on his way to a news conference, minutes after the national court ruling.