Spanish Prime Minister Mariano Rajoy has described as "authoritarian delirium" plans by the ruling parties in the northeastern Catalonia region to declare independence from Spain within 48 hours of a promised referendum Oct. 1, if voters say "yes."

"To all Catalans, to all Spaniards, I want to tell you to maintain confidence in the future as authoritarian delusions... will never defeat the serenity and harmony of our democratic state," Rajoy said at a gathering in Madrid.

His comments came a day after the separatist coalition that governs Catalonia, a wealthy region of 7.5 million inhabitants with its own language and customs, unveiled a bill aimed at ensuring an independence referendum takes place despite Madrid's refusal.

Lawmakers who form the coalition said Catalonia would declare independence "immediately" if the region's voters opt to separate from Spain in the vote planned for October 1. If the "no" side wins, new regional elections will be called, they added.

The bill aims to extract the region from Spain's legal system -- a step aimed at preventing the central authorities from throwing up any legal and practical challenges to organizing a referendum. It will be submitted to a vote in the Catalan regional parliament, where separatists hold a majority, at the end of August.

For years separatist politicians in the region have tried to win approval from Spain's central government to hold a vote similar to Scotland's 2014 independence referendum from Britain -- which was approved by London, though it resulted in a "no" vote. But Madrid has remained steadfast in its opposition to such a vote, considering it a threat to Spain's unity.

The Constitutional Court has already quashed a resolution approved by Catalonia's parliament calling for the referendum to take place. It has also warned Catalonia's elected officials that they would face legal consequences if they took any steps towards holding such a vote.

And while not mentioning Catalonia directly, Defense Minister Maria Dolores de Cospedal issued a thinly-veiled threat on Tuesday, recalling that the army was there to defend democracy and the Constitution, and the "integrity and sovereignty of our country."

In his speech, Rajoy said "Spain is a great country because it counts on the energy of many Spaniards, and many Catalans too who are sensible, democratic and moderate, and increasingly forgotten by a... radical and divisive change of direction."

Catalans are divided on the issue of independence. Some 48.5 percent are against independence and 44.3 percent are in favor, according to a recent regional government poll -- although a large majority want a referendum to take place to settle the matter once and for all.