By Sonya Dowsett and Inmaculada Sanz
MADRID (Reuters) - Catalonia is expected on Wednesday to approve plans for an Oct. 1 referendum on whether to declare independence from Spain, a vote the government says is illegal and has promised to stop.
Catalan lawmakers are due to vote on laws approving the referendum and the legal framework to set up an independent state. The laws will likely be approved because pro-independence parties have a majority in the regional parliament.
Polls in the northeastern region, whose capital is Barcelona, show support for self-rule waning as Spain's economy improves. But the majority of Catalans do want the opportunity to vote on whether to split from Spain.
There will be no minimum turnout requirement to make the result of the vote binding, regional government head Carles Puigdemont said in a recent briefing with journalists. Ballot boxes, voting papers and an electoral census are at the ready, he said.
Under the terms of the new laws, the Catalan parliament will declare independence within 48 hours of a 'yes' vote.
Spanish Prime Minister Mariano Rajoy told a news conference on Monday that the government would come down with all the force of the law to ensure no referendum would go ahead on Oct. 1.
"In one day they hope to do away with the constitution and national sovereignty. They will not do it," he said. "No one can do away with Spanish democracy."
Courts have already suspended from office Catalan politicians who organized a non-binding referendum in 2014, which returned a 'yes' vote on a low turnout.
In addition, a Spanish audit office has demanded the former leader of Catalonia, Artur Mas, and other politicians pay a 5 million euro ($6 million) fine by Sept. 25 for holding the 2014 vote, El Pais newspaper reported on Tuesday.
Catalan leader Puigdemont described the move as intimidation ahead of the planned October referendum.
(Editing by Mark Trevelyan)