MADRID, Spain (CNN) -- Spanish police have arrested 23 leaders of an outlawed Basque pro-independence party on suspicion of aiding the armed separatist group ETA, a judicial source told CNN.
Authorities raided a meeting on Thursday involving the 23 in the Basque town of Segura, where they were suspected of secretly trying to transfer the leadership of the outlawed Batasuna party from veteran activists present to a new set of leaders, who were also present, the source said.
The arrests were seen as part of broad crackdown on ETA and its supporters after ETA formally called off its cease-fire last June.
ETA is blamed for more than 800 deaths over four decades in its fight for Basque independence and is listed as a terrorist group by the United States and the European Union.
Judge Baltasar Garzon, who has long sought to untangle ETA's web of armed fighters, financial support, logistical apparatus and clandestine support from the outlawed Batasuna, ordered the latest arrests, the source said. Watch how arrests make ETA defensive »
The suspects, mainly men but also including at least one woman, could face charges of membership in a terrorist group or other terrorist-related charges, the source.
They are expected to begin arraignments on Sunday before Judge Garzon at the National Court in Madrid, which handles terrorism cases.
About six to eight of the suspects arrested Thursday, well-known names in the Basque radical pro-independence movement, were already under indictment for charges linked to the ETA movement, the source said.
Batasuna is widely considered to be ETA's political wing, which it denies.
ETA announced in March 2006 what it promised would be a "permanent" cease-fire. But efforts to start peace talks with the government faltered during the following months.
Last December, a massive ETA car bomb killed two men at Madrid's airport, destroying a parking garage and causing heavy damage to the airport's newest glass-covered passenger terminal.
The Socialist government considered ETA's cease-fire over with the bombing and halted all peace contacts.
But ETA did not announce the end of the cease-fire for another six months. Since then, police in Spain and France have arrested dozens of suspected ETA members, including senior operatives, and have thwarted various attacks.
ETA has still managed to carry out a few bombings, causing some damage and a few injuries, but without having the same kind of impact nationally that the group had become known for over decades of deadly shooting and bombing attacks which kept Spain on edge. E-mail to a friend
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