The arrest of the suspected members of Batasuna, which has been banned for its ties to the militant group ETA, came just days after a judge in San Sebastian banned two other political organizations -- the Basque Nationalist Action and the Communist Party of Basque Lands -- thought to be fronts for Batasuna, the BBC reported.
The 14 suspects, who were detained in several cities, are accused of trying to reorganize the party and collaborating with a terrorist organization, the British network said.
A demonstration of thousands of supporters of the party was held in Bilbao Sunday. Police broke up the event and arrested several people.
Socialist Prime Minister Jose Luis Rodriguez Zapatero has demanded the separatists unconditionally lay down their arms. Spain will hold a general election March 9.