The pro-independence ruling coalition in Catalonia is submitting a bill to the regional parliament that aims to serve as a transitional constitution should a controversial vote to secede from Spain succeed.

Spain's government says the referendum called for Oct. 1 by the regional Catalan government is unconstitutional and has pledged to prosecute officials who take formal steps to hold it.

Lawmakers representing the ruling regional parties said if the independence bid wins in the referendum, the so-called "juridical transition bill" provides the immediate legal framework for a constituent assembly that would be in charge of founding a new Catalan Republic until elections are held.

The law needs to go through parliamentary vote and is likely to be challenged by central authorities through the Constitutional Court.