Spain's foreign minister says Catalonia's 7.5 million residents would automatically lose their Spanish nationality if the regional government that emerges from this weekend's local elections decides to declare independence.

Jose Manuel Garcia Margallo told reporters Wednesday that when one splits with a country, one loses the benefits of that country. He said the claim that Catalans could maintain Spanish nationality after independence is mistaken.

Voters in the economically powerful northeastern region are to elect regional lawmakers Sunday, with pro-secession parties saying they will establish independence within 18 months if they win a majority. Most opinion polls predict they will.

The government has ruled out any possibility of the region becoming independent, saying secession would be unconstitutional.

Catalonia, whose capital is Barcelona, represents about 18 percent of Spain's economic output.