|Aznar: Taking a tough line|
Aznar said Basque Premier Juan Jose Ibarretxe's push for a referendum would amount to a "capitulation to the blackmail of terror" of armed Basque separatist group ETA.
"Either Ibarretxe withdraws his plan or he will be presenting a challenge to the rule of law," Aznar said in a newspaper interview.
Aznar said the rule of law did not admit challenges from anyone. The law must be complied with. He added there was not sufficient support in the Basque country for Ibarretxe's plan.
Ibarretxe is due to present his proposals for a referendum before the Basque regional parliament in September.
To win approval, he would require the support of banned Basque separatist party Batasuna. The Supreme Court outlawed Batasuna in March as the political wing of ETA.
But Batasuna deputies are allowed to sit in the regional Basque parliament until the end of the current legislative term.
Aznar's tough line against Basque separatists is applauded in most of Spain. But it is viewed with scepticism in the northern Basque country where at least half of a two million people want greater autonomy from Madrid.