MADRID (AP) — The Latest on independence efforts in Spain's Catalonia region (all times local):

2:05 p.m.

Thousands of protesters have gathered outside Catalonia's judiciary body in Barcelona to demand the release of a dozen officials arrested in connection with a planned independence referendum that Spain's central authorities say is illegal.

The crowd has filled a square the size of two soccer fields, with some people climbing onto lampposts while chanting "We will vote!" and "Hello democracy."

Catalan pro-independence civic groups have called for long-term street protests against a surprise police crackdown a day earlier.

Police arrested at least 12 people, mostly Catalan government officials suspected of coordinating the referendum, and seized 10 million ballot papers.

Spanish Prime Minister Mariano Rajoy has warned Catalan officials of "greater harm" if they don't call off the Oct. 1 referendum, but the regional government has vowed to go ahead.

9:40 a.m.

A pro-independence civic group in Catalonia is calling on residents to begin a long-term street protest against Spanish authorities' surprise crackdown on the region's plans to hold a secession referendum.

The Catalan National Assembly's call came hours after Civil Guard police arrested at least 12 people, mostly Catalan government officials, suspected of coordinating the referendum.

The group, a driving force behind the secession movement, urged people to gather at noon Thursday outside the region's justice tribunal and bring tents if needed.

Assembly spokesman Adria Alsina said they would stay until "all the prisoners are released."

Wednesday's arrests triggered demonstrations and some minor disturbances in Barcelona and other Catalan cities overnight.

Regional police had to protect Civil Guard agents as they left one raided building.

Spain says the referendum would be illegal.