Catalonia, the restive northeastern region that is Spain’s economic powerhouse, attempted to hold an independence referendum on Sunday.

The central government in Madrid, with the support of Spanish courts, said the vote was unconstitutional and did everything it could to prevent it. Hundreds were injured in clashes with the police.

Both sides claimed victory after the chaotic voting. The regional government said 90 percent of voters had approved the measure, which officials in Madrid said had been successfully disrupted.