text: Spain 's police seize petrol bombs , arrest five . MADRID 1996-12-06 Spanish police said on Friday they had arrested five people and seized more than 90 petrol bombs during disturbances after a protest in the Basque country against Spain 's constitution . Hooded protesters threw burning bottles and other objects at police in Pamplona after the protest organised by Herri Batasuna , the political wing of Basque separatist group ETA . Police also confiscated eight kg ( 18 lb ) of screws , balaclavas and spray paint cans . The protest , which attracted several thousand supporters , coincided with the 18th anniversary of Spain 's constitution .