Vitoria, Spain - Basque authorities will appeal to European tribunals against a ruling by Spain's Constitutional Court which blocked a planned referendum on the self-determination of the northern region, Basque regional Prime Minister Juan Jose Ibarretxe said Friday.

The Basque government "respected" the ruling, but regarded it as undemocratic and would not "resign," Ibarretxe said.

The Basque parliament had previously authorized the referendum-like vote to be staged on October 25. The Spanish government lodged a complaint at the Constitutional Court, the country's highest court alongside the Supreme Court.

In an unanimous ruling late Thursday, the court said the vote was unconstitutional, because only the Spanish government had the right to authorize referendums.

The Basque premier's office immediately accused the court of partiality. "The judiciary has let pass an opportunity to demonstrate its independence and shown once again that is penetrated by politics," the office said a communique released overnight.

The vote would have asked the Basques whether they approved of a negotiated solution to Spain's conflict with the militant Basque separatist group ETA and of Basque party talks on the region's right to decide its own future.

Spanish Prime Minister Jose Luis Rodriguez Zapatero's government feared that the referendum would encourage separatism in the region of 2.1 million people.

Ibarretxe believes that an open discussion about options including independence would help to solve the problem of ETA, which has killed more than 820 people in its four-decade campaign for a sovereign Basque state. (dpa)