Spain’s highest authority on such matters, the Constitutional Court, halted the move by the Catalan parliament while judges now consider whether it is against the country’s constitution.
The central government in Madrid claims politicians in Catalan only have the power to call an election not a referendum.
Last week, Spain’s Attorney General, José Manuel Maza, issued a lawsuit against the president of Catalonia, Carles Puigdemont.
Support for independence in Catalan has diminished in recent years, according to polls, but the majority of citizens there want to vote on the issue.
Most of Catalonia’s 948 mayors have already pledged to allow the use of public spaces for the proposed referendum but the Mayor of Barcelona, Ada Colau, has asked for assurances that civil servants involved will not risk losing their jobs.
On Monday hundreds of thousands of people rallied in Barcelona to support the secession from Madrid.