BARCELONA, Spain — Striking workers, students and hundreds of thousands of protesters took to the streets of Barcelona and other Catalan towns Tuesday to protest police violence, adding pressure to Spain’s unprecedented political crisis as central authorities weigh responses to separatists’ plans to push ahead with secession.

Separatist leaders in Catalonia have vowed to declare independence in the northeastern region this week following Sunday’s disputed referendum.

The central government has declared the vote illegal and invalid, but Prime Minister Mariano Rajoy has not disclosed what his response to the independence bid will be, or if he intends to go as far as suspending the region’s self-government.

The city’s urban guard said that 700,000 people joined Tuesday afternoon’s marches in Barcelona, after thousands more took part in scattered protests in the morning.

With protesters still in the streets, Spain’s King Felipe VI made a television appearance in the evening and accused authorities in Catalonia of deliberately bending the law and undermining coexistence, adding that the Spanish state has a duty to ensure unity and constitutional order in the country.

“Today, Catalan society is fractured,” Felipe said in his address to the nation, referring to the political crisis as “very serious moments for our democratic life.”

Catalan officials say that 90 percent of the 2.3 million people who voted Sunday were in favor of independence. But fewer than half of those eligible to vote turned out. The vote was boycotted by most of Spain’s national parties on grounds that it was illegal and lacked basic guarantees, such as transparency, a proper census or an independent electoral governing body.

The king’s call for unity and the blame put on the Catalan authorities was interpreted as laying the ground for an upcoming response from Rajoy.