Artur Mas said today the referendum would ask voters first if they want Catalonia to be a state and if so, should it be independent. The distinction between a state and an independent state has not been clarified.
Under Spain’s constitution only the central government can call a referendum and Prime Minister Mariano Rajoy recently rejected a request by Mr Mas to allow one.
Polls indicate that Catalans are roughly evenly split on independence.
The European Union and Nato have warned Catalonia it would be excluded if it seceded.