Spain's supreme court has denied legal status to a newly-formed Basque political party, Sortu.
The court said it will release details of its ruling in the next few days.
The Spanish government asked the court to rule against legitimizing the party, saying it has not fully distanced itself from the armed Basque separatist group, ETA. The court's decision means Sortu will not be allowed to take part in Basque regional elections in May.
Basques regard Sortu as the successor to the outlawed political party, Batasuna.
ETA has killed more than 820 people in its four decade-long campaign for Basque independence in northern Spain and southern France. The group declared a cease-fire in January. But the Spanish government immediately rejected it, saying ETA made no pledges to disarm.
Spain, the European Union, and United States regard ETA as a terrorist group.
Some information for this report was provided by Reuters.