http://www.ajc.com/news/content/news/ap/ap_story.html/Intl/AP.V9941.AP-Spain.html
The tape–along with the arrest of three Moroccan and two Indian suspects–provided the strongest indication yet of an Islamic link to the attack on one of Washington’s staunchest allies in Iraq. The Spanish government, however, said it could not confirm the tape’s authenticity.
The announcement came just hours before polls were to open Sunday in general elections weighed down by debate over the attack. Thousands of people rallied overnight against the governing Popular Party, saying it should be thrown out of power for drawing al-Qaida’s wrath.
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A London-based Arabic newspaper had earlier received a claim of responsibility in al-Qaida’s name; but the government had been reluctant to blame the Islamic group, saying the Basque separatist group ETA was also a suspect. ETA denied responsibility.