The Supreme Court in Spain has banned hundreds of candidates from standing in local elections on 27 May in the northern Basque region.
They were accused of being connected to the armed separatist group, Eta.
The court ruled that a little-known group, Abertzale Socialistak, was in fact a front for the banned political wing of Eta, Batasuna.
The court is still considering whether to ban another political group, Basque National Action.
Batasuna has been banned since 2003, but in 2001 won 10% of the vote in regional elections.
The 246 supposedly apolitical "citizen lists" of Abertzale Socialistak were banned under a law preventing the continuation of a banned party.
However, seven other independent lists will be allowed at the elections.
Eta is seeking an independent state in northern Spain and south-west France.
The group has been waging an armed campaign for more than 30 years and is blamed for more than 800 deaths.