A backpack filled with explosives was found Saturday near a town in French Basque country, French police officials said. A passer-by came upon the backpack, which was partially buried, in a mountainous area outside the village of Souraide - near the Spanish border - and alerted authorities, police officials said. It was not immediately clear who left the backpack, but police investigators refused to immediately implicate the armed Basque group, ETA. ETA, an acronym for Basque Homeland and Freedom in the Basque language, has been waging a violent campaign since the late 1960s for an independent state. Although mainly active in Spain, the group is also present in the Basque region of southern France.