The leader of Spain's wealthy Catalonia region signed a decree on Monday calling early parliamentary elections on September 27 which he has said will act as proxy vote on independence.

The decree signed by Catalan president Artur Mas made no reference to independence for the northeastern region, which accounts for a fifth of Spain's economic output. But Mas has said that if pro-secession parties win a majority, they will aim to split from Spain within 18 months.