[JURIST] The Spanish Justice Ministry Tuesday filed a challenge in Spain's Constitutional Court [official website, in Spanish] to block a planned Basque region referendum on increased autonomy. The referendum, approved by the Basque Parliament last month, will ask citizens whether the Basque government [official website] should begin negotiations for increased regional self-determination and whether it should initiate peace talks with Basque separatist group ETA [BBC backgrounder; JURIST news archive], provided that ETA renounces violence. The planned referendum was officially recorded as law earlier Tuesday. The national government has denounced it as illegal. AFP has more.

ETA has been waging a terrorist campaign in pursuit of an independent Basque state since the 1960s. Recently, the group was implicated in a December 2006 Madrid airport bombing [CNN report] that killed two Ecuadoran men and shattered a 15-month ETA ceasefire. ETA has been blamed for more than 800 deaths in bombings and attacks.