The Spanish Supreme Court has published a verdict confirming it was banning Batasuna, seen as the political wing of Basque armed separatist group ETA.
The ban - sought by the government in Madrid and accepted by the Supreme Court on March 17th - is the first move to outlaw a political party in Spain since the country returned to democracy in 1978 following the death of far-right dictator Francisco Franco.
The verdict also confirmed the court's decision to ban two radical separatist Basque parties that preceded Batasuna - Herri Batasuna and Euskal Herritarrok.
The document said the sole aim of the three parties was to "provide legal cover and political support" to ETA, which has been fighting for 35 years for an independent Basque homeland comprising parts of northern Spain and southwestern France.
The court ruled that all activities by the three groups should cease immediately, that they should be taken off the national register of political parties and that their assets should be liquidated.
The ban has the overwhelming support of the parliament in Madrid.
But it is staunchly opposed by the moderate Basque Nationalist Party (PNV), which governs the wealthy northern region, and many people who live there.
The PNV said silencing Batasuna, which regularly obtains between 10 and 20 per cent of the vote in Basque regional elections, would deprive local people of their democratic right to choose their politicians.
AFP