Catalan regional lawmakers are debating regional President Carles Puigdemont's latest promise to hold another independence referendum next September with or without agreement from Spain.

Puigdemont launched the proposal Wednesday during a debate on his presidency, saying he would seek Spain's backing but intended holding it anyway if Spain persists in ruling it out.

Pro-secession parties hold a slim majority in the Catalan regional parliament but polls show the economically powerful northeastern region is roughly divided over splitting from Spain.

Opposition lawmakers on Thursday argued that the referendum would be illegal and would not be recognized.

Catalonia held a non-binding secession vote in 2014, when around 1.6 million people voted in favor of independence. The Constitutional Court ordered its suspension and most of the region's 5.4 million eligible voters didn't participate.